Extrusion granulator template preheating system and extrusion granulator template mounting method

Abstract

The invention relates to the technical field of extrusion granulation, and provides an extrusion granulator template preheating system and an extrusion granulator template mounting method.The extrusion granulator template preheating system comprises a heating device arranged on an outlet pipeline of a circulating pump; the oil supply device is connected with an oil path pipeline of the heating device; the nitrogen sealing device is arranged on a nitrogen pipeline of the oil supply device and is connected with the oil inlet end of the oil supply device through a pipeline; the heating device comprises a plurality of oil inlet metal hoses and a plurality of oil outlet metal hoses, and the oil inlet metal hoses and the oil outlet metal hoses are connected with the heating runner of the template through flanges; the electric heater is arranged on an oil inlet pipeline of the oil inlet metal hoses; the oil supply valve is arranged on an oil outlet pipeline of the electric heater; the oil return valve is arranged on an oil return pipeline of the plurality of oil outlet metal hoses; and the communicating valve is arranged between the outlet of the electric heater and the oil supply device. Rapid and safe installation of the formwork is achieved, and the operation risk and the formwork loss rate are reduced.

Description

Technical Field

[0001] This application relates to the field of extrusion granulation technology, and more specifically, to an extrusion granulator template preheating system and an extrusion granulator template installation method. Background Technology

[0002] Currently, existing extrusion granulators commonly use a "hot disassembly, cold installation" process when replacing die plates. This involves disassembling the old die plate at the equipment's operating temperature, cooling the entire machine to room temperature before installing the new die plate, and finally heating it back to operating temperature. This process is cumbersome and time-consuming, typically taking 48 hours, resulting in prolonged production shutdowns and severely restricting production efficiency and continuity. More problematic is the significant temperature difference between the room-temperature new die plate and the heated die shell during the "cold installation" process. This causes the die plate to be constrained during thermal expansion, preventing the complete release of thermal stress. This residual thermal stress continues to act on the weakest area of ​​the die plate—the granulation zone. This can lead to issues such as exceeding the surface flatness standard of the granulation zone, accelerating wear on the cutter and die plate, and shortening their lifespan; or even causing the granulation zone to crack, rendering the expensive die plate unusable. Furthermore, the entire replacement process is lengthy, and personnel working near high-temperature equipment face significant risks. Therefore, there is an urgent need for a technical solution that can enable rapid and safe replacement of the template and effectively prevent the template from being damaged by thermal stress, so as to improve the operating efficiency, template service life and operational safety of the extrusion granulator. Summary of the Invention

[0003] This application aims to at least solve the technical problems in the related technologies, such as the risk of excessive flatness or scrap of the template granulation belt surface due to temperature differences during the traditional hot disassembly and cold assembly process of templates, and the fact that the entire template replacement process takes 48 hours, which is a long operation time and has high operation risk, seriously affecting the long-term stable operation of the equipment and causing a significant reduction in the production efficiency of the equipment.

[0004] To solve the above-mentioned technical problems, this application is implemented as follows: In a first aspect, this application provides a preheating system for an extrusion granulator die, comprising: a heating device installed on the outlet pipeline of a circulating pump for circulating and heating heat transfer oil to the die to be installed; an oil supply device connected to the oil pipeline of the heating device for supplying and recovering heat transfer oil to the heating device; and a nitrogen sealing device installed on the nitrogen pipeline of the oil supply device and connected to the oil inlet of the oil supply device via a pipeline for sealing and isolating direct contact between air and heat transfer oil by filling with nitrogen; wherein the heating device includes: multiple inlet metal hoses and multiple outlet metal hoses, and multiple inlet metal hoses and multiple outlet metal hoses The metal hoses are connected to the heating channels of the template via flanges, used for introducing and discharging heat transfer oil to heat the template; the electric heater is installed on the inlet lines of the multiple inlet metal hoses, and its outlet line is connected to the multiple inlet metal hoses via flanges; the oil supply valve is installed on the outlet line of the electric heater and connected to the multiple inlet metal hoses, used for conveying the heated heat transfer oil; the oil return valve is installed on the return lines of the multiple outlet metal hoses and connected to the oil supply device via pipeline, used for returning the heat-exchanged heat transfer oil to the oil supply device; and the connecting valve is installed between the outlet of the electric heater and the oil supply device.

[0005] This application provides a preheating system for an extrusion granulator template. Through the coordinated operation of an integrated preheating, circulation, and control system, it achieves multiple functions including rapid and safe template installation and thermal stress control. In the scenario of uniform template preheating, the preheating system consists of an oil supply device, a heating device, and a nitrogen sealing device, forming an independent skid-mounted circulation unit. An electric heater heats the heat transfer oil, which is then driven by a circulation pump and delivered through multiple inlet metal hoses to the internal heating channel of the template to be installed. This circulates and heats the template, and finally, the heat transfer oil returns to the system through multiple outlet metal hoses, forming a closed loop. This design separates the template heating process from the main machine system, completing it independently outside the machine. In the scenario of precise temperature control and oil protection, the system adopts a segmented heating method. The temperature controller gradually increases the temperature in 25°C increments and maintains a constant temperature at each stage, ensuring uniform and slow template expansion, fully releasing manufacturing and installation stress, and fundamentally avoiding thermal deformation. Simultaneously, the nitrogen sealing device fills the high-level storage tank with nitrogen gas, isolating the heat transfer oil from air, effectively preventing oxidation and deterioration at high temperatures, and extending its service life. In rapid and safe installation scenarios, after preheating, the heat transfer oil in the template and pipelines is completely drained through the drain valve to facilitate subsequent safe operations. During installation, operators use a symmetrical, cross-tightening method from the inside out, tightening the bolts twice to the target torque value. This ensures that the template can expand freely and evenly during tightening, allowing for complete release of thermal stress and guaranteeing that the surface flatness of the granulation belt permanently meets the standards. Ultimately, this extrusion granulator template preheating system reduces the traditional 48-hour replacement time to approximately 2 hours and significantly reduces operational risks and template wear rate.

[0006] Secondly, this application proposes a method for installing an extrusion granulator template, employing an extrusion granulator template preheating system as described above. This system heats the template to the installation temperature before installation, and includes the following steps: S1, System connection and circulation establishment step: Connect the template with multiple inlet and outlet metal hoses, and start the oil supply and heating devices to establish a heat transfer oil circulation; S2, Segmented heating and constant temperature step: Start the electric heater to heat the template in segments according to a preset temperature gradient, and maintain a constant temperature in each segment until the template temperature reaches the target installation temperature; S3, Oil drainage and disassembly step: Stop heating, drain the heat transfer oil from the extrusion granulator template preheating system and the template, and disassemble the inlet and outlet metal hoses connected to the template; S4, Hot installation step: Hoist the template preheated to the target temperature to the extrusion granulator die head housing position, and complete the installation using a bolt tightening method combining inside-out and symmetrical fastening.

[0007] The extrusion granulator template installation method provided in this application, being used in the extrusion granulator template preheating system of the above scheme, has all the beneficial effects of the extrusion granulator template preheating system, which will not be elaborated here.

[0008] Additional aspects and advantages of this application will become apparent in the following description or may be learned by practice of this application. Attached Figure Description

[0009] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the oil circuit structure of the preheating system for the extrusion granulator template according to one embodiment of this application; Figure 2 This is a flowchart illustrating a method for installing a template in an extrusion granulator according to an embodiment of this application; Figure 3 This is a schematic diagram showing the sequence of bolt tightening steps during the installation of a template according to an embodiment of this application.

[0010] in, Figure 1 The correspondence between the reference numerals and component names in the attached drawings is as follows: 100 Extrusion Granulator Template Preheating System, 101 Heating Device, 102 Oil Supply Device, 103 Nitrogen Sealing Device, 1 First Check Valve, 2 Nitrogen Valve, 3 Oil Filling Valve, 4 High-Level Storage Tank, 5 Main Oil Inlet Valve, 6 First Oil Valve, 7 Filter, 8 Second Oil Valve, 9 Cross-line Valve, 10 First Pressure Gauge, 11 Circulating Pump, 12 Second Check Valve, 13 Flow Meter, 14 Second Pressure Gauge, 15 Main Oil Outlet Valve, 16 Electric Heater, 17 Temperature Controller, 18 Oil Supply Valve, 19 Connecting Valve, 20 Safety Valve, 21 First Exhaust Valve, 22 First Oil Inlet Pipe, 23 Second Oil Inlet Pipe, 24 Third Oil Inlet Pipe, 25 Fourth Oil Inlet Pipe, 26 First Drain Valve, 27 Template, 28 Temperature Gauge, 29 First Oil Outlet Pipe, 30 Second Oil Outlet Pipe, 31 Third Oil Outlet Pipe, 32 Fourth Oil Outlet Pipe, 33 Second Drain Valve, 34 Return Oil Valve, 35 Second Exhaust Valve. Detailed Implementation

[0011] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0012] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0013] The following reference Figures 1 to 3 This application describes a preheating system 100 for an extrusion granulator template and a method for installing an extrusion granulator template according to some embodiments of the present application.

[0014] According to the first aspect of this application, Figure 1As shown, one embodiment of this application provides a preheating system 100 for an extrusion granulator template, comprising: a heating device 101, installed on the outlet pipeline of a circulating pump 11, for circulating and heating heat transfer oil to the template 27 to be installed; an oil supply device 102, connected to the oil pipeline of the heating device 101, for supplying and recovering heat transfer oil to the heating device 101; and a nitrogen sealing device 103, installed on the nitrogen pipeline of the oil supply device 102, connected to the oil inlet of the oil supply device 102 via a pipeline, for sealing and isolating direct contact between air and heat transfer oil by filling with nitrogen; wherein, the heating device 101 includes: multiple inlet metal hoses and multiple outlet metal hoses, the multiple inlet metal hoses Multiple oil outlet metal hoses are connected to the heating flow channel of template 27 via flanges for introducing and discharging heat transfer oil to heat template 27; electric heater 16 is installed on the oil inlet line of multiple oil inlet metal hoses, and its oil outlet line is connected to multiple oil inlet metal hoses via flanges; oil supply valve 18 is installed on the oil outlet line of electric heater 16 and connected to multiple oil inlet metal hoses for conveying heated heat transfer oil; oil return valve 34 is installed on the oil return line of multiple oil outlet metal hoses and connected to oil supply device 102 via pipeline for returning the heat-exchanged heat transfer oil to oil supply device 102; connecting valve 19 is installed between the outlet of electric heater 16 and oil supply device 102.

[0015] Specifically, such as Figure 1As shown, the extrusion granulator template preheating system 100 provided in the embodiments of this application includes a heating device 101, an oil supply device 102, and a nitrogen sealing device 103. The heating device 101 is installed on the outlet pipeline of the circulating pump 11 and is used to circulate and heat the heat transfer oil to the template 27 to be installed. The oil supply device 102 is connected to the oil pipeline of the heating device 101 and is used to supply and recover heat transfer oil to the heating device 101. The nitrogen sealing device 103 is installed on the nitrogen pipeline of the oil supply device 102 and is connected to the oil inlet end of the oil supply device 102 via a pipeline, used to seal and isolate direct contact between air and heat transfer oil by filling with nitrogen. In addition, the heating device 101 includes multiple inlet metal hoses, multiple outlet metal hoses, an electric heater 16, a temperature controller 17, an oil supply valve 18, a return oil valve 34, and a connecting valve 19. The temperature controller 17 is interlocked with the electric heater 16 to set and control the heating temperature of the heat transfer oil. Multiple inlet and outlet metal hoses are connected to the heating channel of the template 27 via flanges to allow the heat transfer oil to flow in and out to heat the template 27. The electric heater 16 is installed on the inlet line of the multiple inlet metal hoses, and its outlet line is connected to the multiple inlet metal hoses via flanges. The oil supply valve 18 is installed on the outlet line of the electric heater 16 and connected to the multiple inlet metal hoses to deliver the heated heat transfer oil. The return valve 34 is installed on the return line of the multiple outlet metal hoses. It is connected to the oil supply device 102 via a pipeline to return the heat transfer oil after heat exchange to the oil supply device 102; the connecting valve 19 is set between the outlet of the electric heater 16 and the oil supply device 102, so that when the heating device 101 has a heat transfer oil leak or other faults, it can bypass the heating device 101 and allow the heat transfer oil to circulate by itself, providing an opportunity to deal with the fault of the heating device 101 without interrupting the operation of the entire preheating system and the circulation of the heat transfer oil, thereby ensuring the convenience and safety of critical maintenance operations, minimizing the production preparation time delay caused by maintenance, and improving the overall availability of the entire set of equipment.

[0016] In this way, the heat transfer oil supplied and driven by the oil supply device 102 is heated by the electric heater 16 of the heating device 101 and then transported to the heating channel of the template 27 to be installed through the oil inlet metal hose, where it is heated evenly. After heat exchange, the heat transfer oil returns to the oil supply device 102 through the oil outlet metal hose, forming an independent closed-loop preheating circuit. The nitrogen sealing device 103 effectively isolates the contact between air and high-temperature heat transfer oil by filling the system with nitrogen, preventing oil oxidation and ensuring long-term stable operation of the system. This preheating system separates the heating process of the template 27 from the main machine, realizing independent and controllable preheating of the template 27 outside the machine. This provides a foundation for subsequent rapid and safe hot installation, thereby avoiding the problem of deformation or cracking of the template 27 due to thermal stress concentration caused by temperature difference in the traditional "cold installation" method.

[0017] Compared with existing technologies, the preheating system 100 for extrusion granulators provided in this application has the following advantages: the heating device 101 and the oil supply device 102 utilize electrical energy converted into heat energy to heat the heat transfer oil. The circulating heat transfer oil heats the template 27, stabilizing its temperature at the installation temperature, thus achieving hot installation of the template 27. This avoids abnormal deformation of the granulation belt of the template 27 during the heating process after cold installation, extending the service life of the template 27, improving production efficiency, and ensuring long-term stable operation of the production equipment. Furthermore, the installation process of the heated template 27 is short, requiring only 2 hours, saving maintenance time and reducing operational risks. Additionally, the nitrogen sealing device 103 ensures that the heat transfer oil does not oxidize due to high temperatures, extending its service life.

[0018] Specifically, extrusion granulation is an indispensable process in the polyolefin industry, belonging to the post-processing stage of the product. It determines the final quality of the polyolefin product, and the extrusion granulator is an essential core piece of equipment in this process. Taking a polypropylene extrusion granulator as an example, polypropylene powder is conveyed to the extrusion granulator hopper through a powder conveying system, and then enters the extrusion granulator cylinder. After being melted, mixed, sheared, homogenized, and pressurized by the twin-screw extruder, the material enters the discharge section of the extrusion granulator. After being pressurized by a melt pump and impurities removed by a screen changer filter, it is extruded from the die holes. The coaxially rotating pelletizer cutter cuts the extruded molten resin into regularly shaped granules. After being cooled and solidified by the pelletizing water in the pelletizing water chamber, the granules are carried away by the water flow to a centrifugal dryer for separation and drying. The die of the extrusion granulator determines the specifications, dimensions, and shape of the polyolefin product and is the main equipment for product molding. The template mainly consists of the template body, the granulation belt, and a waterproof and heat-insulating pad. Small holes of a certain diameter (i.e., die holes) are arranged on the surface of the granulation belt for the molten resin to be extruded in strands. The molten resin extruded from the die holes is cut into regularly shaped and uniformly sized granules by the high-speed rotation of the pelletizer's cutter. During the installation process, insufficient heating and expansion time, or incorrect bolt tightening methods, can lead to incomplete release of thermal stress generated in the template. This residual thermal stress acts on the surface of the granulation belt, and over time, the surface flatness of the granulation belt exceeds the standard, resulting in severe wear of the cutter and template, and a reduced service life. In severe cases, cracks may appear on the surface of the granulation belt, rendering the template unusable.

[0019] Currently, in the industry, extrusion granulators generally need to be replaced after one year of use. For products with higher melt flow index, the lifespan of the granulators is less than one year. Most products in the polyolefin industry operate at temperatures above 200℃ in extrusion granulators. The most basic principle for replacing extrusion granulator granulators is hot disassembly followed by cold installation. This means removing the granulator at its operating temperature, then cooling the granulator until it reaches room temperature, reinstalling the new granulator, and then heating the granulator back to its operating temperature. This entire granulator replacement process takes 48 hours, meaning the entire unit needs to be shut down for 48 hours, severely impacting the long-term stable operation of the unit and significantly reducing its production efficiency. The main reasons for hot disassembly are: firstly, at operating temperature, the bolts fixing the granulator are in a state of thermal expansion, allowing for easy loosening and removal; secondly, as the temperature decreases, the bolts shorten due to cooling, causing the tightening torque to increase exponentially, making removal impossible. Secondly, the molten resin in the template feeding chamber and die head housing is in a molten state at the operating temperature, making it very easy to break and clean. After the temperature drops, the molten resin cools and solidifies, making it impossible to separate the template and die head housing smoothly, and also preventing the smooth cleaning of the molten resin in the template feeding chamber and die head housing. Thirdly, after the extrusion granulator's operating temperature drops, the temperature probe on the template cannot be easily removed. The main reasons for cold assembly are: First, there is no preheating facility for the template to be assembled; it can only be assembled onto the die head housing after the extrusion granulator has cooled to room temperature. Second, to ensure that the template and die head housing expand synchronously, the die head housing must be cooled to the same temperature as the template to be assembled. If the template at room temperature is locked together with the high-temperature die head housing, the template cannot expand during the heating process, leading to abnormal deformation in the weakest area of ​​the template, the granulation zone. This can result in the granulation zone's surface flatness exceeding the standard value, or even the template being scrapped due to cracking of the granulation zone.

[0020] To address the shortcomings of existing technologies, such as Figure 1As shown, the extrusion granulator die preheating system 100 provided in this application is designed with a skid-mounted heat transfer oil circulation heating unit independent of the main extrusion granulator. This system supplies and drives the heat transfer oil medium through the oil supply device 102 (including a high-level storage tank 4, a circulation pump 11, etc.), which is precisely heated by the electric heater 16 of the heating device 101. The oil is then transported through multiple inlet metal hoses to the heating channel inside the die 27 to be installed, where it is heated comprehensively and uniformly. The heat transfer oil, after heat exchange, returns to the system through multiple outlet metal hoses, forming a complete closed-loop preheating cycle. During this process, the nitrogen sealing device 103 effectively isolates the system from air by filling it with nitrogen, preventing the heat transfer oil from oxidizing and deteriorating at high temperatures. This design achieves coordination between the die 27 preheating process and the main machine's operating status, allowing the die 27 to be independently and controllably preheated to a working temperature matching the main machine die housing before installation. This fundamentally avoids the enormous thermal stress generated by the combination of the room-temperature template 27 and the high-temperature shell in the traditional "cold installation" process, thereby eliminating the risk of deformation or cracking of the template 27 granulation zone and creating the necessary conditions for subsequent safe and rapid "hot" installation.

[0021] In specific applications, the extrusion granulator template preheating system 100 provided in this application also includes a temperature gauge 28, which is installed on the template 27 to directly monitor the real-time temperature of the template 27.

[0022] In some embodiments, optionally, such as Figure 1 As shown, the heating device 101 further includes: a first drain valve 26 and a second drain valve 33, the first drain valve 26 being installed on the inlet metal hose and the second drain valve 33 being installed on the outlet metal hose, for discharging the heat transfer oil in the inlet metal hose, the outlet metal hose and the heating channel of the template 27 after heating is completed; a first vent valve 21 and a second vent valve 35, the first vent valve 21 being installed on the vent line of the inlet metal hose and the second vent valve 35 being installed on the vent line of the outlet metal hose, for discharging the oil vapor in the inlet metal hose and the outlet metal hose when establishing the heat transfer oil circulation.

[0023] Specifically, such as Figure 1As shown, the first drain valve 26 is installed on the inlet main pipe, and the second drain valve 33 is installed on the outlet main pipe. That is, the first drain valve 26 and the second drain valve 33 are respectively located at the low points of the inlet and outlet metal hoses, forming the system's venting interface. By opening and closing the valves, after the preheating process, the heat transfer oil retained in the pipes and the complex flow channels of the template 27 can be completely and smoothly discharged. The first vent valve 21 and the second vent valve 35 are correspondingly installed at the high points of the inlet and outlet metal hoses. Their function is to provide a dedicated escape channel for air that has expanded due to heat or mixed into the pipes during the critical stages of initial system operation and establishing oil circulation. In this way, on the one hand, the exhaust valve effectively prevents problems such as poor circulation, uneven heating, or even abnormal system pressure caused by "air resistance", ensuring the stability and efficiency of the preheating process; on the other hand, the drain valve ensures that there is no residual hot oil in the template 27 and connecting pipes before the installation operation, which not only avoids the risk of burns caused by high temperature oil, but also clears the way for the subsequent quick and clean disassembly of the metal hose and hoisting of the template 27, thus significantly improving the safety and convenience of the entire replacement operation.

[0024] In specific applications, the heating device 101 also includes a safety valve 20, which is installed on the heating pipeline (such as the outlet of the electric heater 16) for system overpressure protection.

[0025] In some embodiments, optionally, such as Figure 1 As shown, the oil supply device 102 includes: a high-level storage tank 4, connected to the nitrogen sealing device 103 via a nitrogen pipeline, which is used to store heat transfer oil and maintain a nitrogen atmosphere; a refueling valve 3, installed on the high-level storage tank 4, used for initial refueling or replenishment of heat transfer oil; a main inlet valve 5, installed on the outlet pipeline of the high-level storage tank 4; a filter 7, connected to the high-level storage tank 4 via a first oil valve 6 and a second oil valve 8 connected in series on the outlet pipeline of the main inlet valve 5; a circulation pump 11, installed on the outlet pipeline of the second oil valve 8, used to drive the heat transfer oil circulation, with a second check valve 12, a flow meter 13, and a second pressure gauge 14 connected in series on the outlet pipeline of the circulation pump 11; a first pressure gauge 10, installed on the inlet pipeline of the circulation pump 11, used to monitor the pump inlet pressure; and a main outlet valve 15, connected in series on the outlet pipeline of the circulation pump 11, connected to the inlet pipeline of the electric heater 16.

[0026] Specifically, such as Figure 1As shown, the high-level storage tank 4 serves as the core of the system for oil storage and pressure stabilization. Its top is connected to the nitrogen sealing device 103 via a nitrogen pipeline, maintaining a nitrogen atmosphere inside to protect the heat transfer oil. The refueling valve 3 on the tank facilitates initial oil filling and daily replenishment. The main oil inlet valve 5 controls the main channel for oil delivery from the storage tank to the working pipeline. After the heat transfer oil flows out, it passes through a filtration unit consisting of a first oil valve 6, a filter 7, and a second oil valve 8 connected in series. The filter 7 effectively removes impurities such as coking deposits that may occur during high-temperature operation, ensuring oil cleanliness. The circulating pump 11 serves as the system's power source. The first pressure gauge 10 on its inlet pipeline monitors the suction pressure to prevent cavitation. The second check valve 12, installed sequentially on the pump outlet pipeline, prevents oil backflow. The flow meter 13 monitors the circulating flow rate to assess heating efficiency, and the second pressure gauge 14 displays the pump outlet and system main circuit pressure. The main oil outlet valve 15 finally delivers the pressurized and purified heat transfer oil to the heating device 101. Through the synergy of the aforementioned components, the oil supply device 102 provides a continuous, stable, clean, and parameter-controllable heat transfer oil circulation flow for the entire preheating system, ensuring reliable heat supply and safe operation during the preheating process of the template 27. The configuration of the filter 7 and various monitoring instruments also greatly extends the system maintenance cycle and improves the controllability of operation.

[0027] In some embodiments, optionally, such as Figure 1 As shown, the oil supply device 102 also includes a crossover valve 9, one end of which is connected to the inlet pipeline of the first oil valve 6, and the other end is connected to the outlet pipeline of the second oil valve 8.

[0028] Specifically, such as Figure 1 As shown, the crossover valve 9 is connected in parallel to both ends of the filtration branch formed by the first oil valve 6, filter 7, and second oil valve 8 connected in series, creating an optional fluid bypass path. The filtration branch can be activated, isolated, or bypassed by switching the valves. During normal system operation, the crossover valve 9 is closed, and the heat transfer oil must flow through the filter 7 for purification. When cleaning or replacing the filter element of filter 7 is required, the crossover valve 9 can be opened first to establish bypass, and then the first oil valve 6 and second oil valve 8 can be closed to safely isolate filter 7 from the main circuit. This design enables online maintenance of filter 7, allowing cleaning or replacement of the filter element without interrupting the operation of the entire preheating system and the circulation of the heat transfer oil. This ensures the convenience and safety of critical maintenance operations, minimizes production preparation time delays caused by maintenance, and improves the overall availability of the entire equipment.

[0029] In some embodiments, optionally, such as Figure 1 As shown, the nitrogen sealing device 103 includes: a first check valve 1, connected to the nitrogen pipeline leading to the high-level storage tank 4; and a nitrogen valve 2, the inlet of which is connected to the outlet pipeline of the first check valve 1, and the outlet of which is connected to the pipeline of the high-level storage tank 4.

[0030] Specifically, such as Figure 1 As shown, the first check valve 1 and the nitrogen valve 2 are connected in series on the pipeline between the external nitrogen source and the elevated storage tank 4. The first check valve 1 ensures that nitrogen can only flow into the elevated storage tank 4 in one direction, effectively preventing the backflow of gas or oil mist inside the tank, thus forming the first sealing barrier. The nitrogen valve 2 serves as the main control valve, used to precisely regulate the flow rate and pressure of nitrogen. During operation, by opening the nitrogen valve 2, nitrogen is injected into the gas phase space at the top of the elevated storage tank 4 through the first check valve 1, replacing and isolating the air. In this way, during system operation, a stable slightly positive pressure nitrogen protective atmosphere can be formed and maintained above the surface of the heat transfer oil, thereby effectively isolating oxygen and fundamentally preventing the oxidation, cracking, and deterioration of the heat transfer oil under high-temperature cycling conditions, significantly extending the service life of the heat transfer oil, and also helping to maintain stable system pressure.

[0031] In some embodiments, optionally, such as Figure 1 As shown, the multiple inlet metal hoses include a first inlet pipe 22, a second inlet pipe 23, a third inlet pipe 24, and a fourth inlet pipe 25; the multiple outlet metal hoses include a first outlet pipe 29, a second outlet pipe 30, a third outlet pipe 31, and a fourth outlet pipe 32.

[0032] Specifically, such as Figure 1 As shown, the inlet ends of the first oil inlet pipe 22, the second oil inlet pipe 23, the third oil inlet pipe 24, and the fourth oil inlet pipe 25 are connected to the hot oil main pipe after the oil supply valve 18, and their outlet ends are connected to the corresponding heating channel inlets on the template 27 via flanges. The inlet ends of the first oil outlet pipe 29, the second oil outlet pipe 30, the third oil outlet pipe 31, and the fourth oil outlet pipe 32 are connected to the outlets of each heating channel of the template 27 in the same manner, and their outlet ends are connected to the return oil main pipe before the return oil valve 34. This constitutes a parallel multi-channel circulating heating network. High-temperature heat transfer oil is simultaneously and evenly delivered to each heating area inside the template 27 through multiple independent oil inlet paths, and synchronously recovered through multiple corresponding oil outlet paths. This greatly optimizes the heat exchange area and flow distribution, ensures the uniformity and efficiency of the overall heating of the template 27, and effectively avoids local temperature differences and thermal stress concentrations that may be caused by a single path or uneven flow. This provides a reliable guarantee for the uniform expansion of the template 27 and subsequent stable installation.

[0033] In practical applications, the extrusion granulator template preheating system 100 provided in this application adopts a skid-mounted structure, with all components arranged on a single skid. The skid is equipped with universal casters, allowing for flexible movement and facilitating template 27 replacement. Figure 1As shown, heat transfer oil is first added to the high-level storage tank 4 through the refueling valve 3. Heat transfer oil is highly susceptible to oxidation under high-temperature operation, leading to deterioration. Therefore, the high-level storage tank 4 is protected by nitrogen purging through the first check valve 1 and nitrogen valve 2 to prevent direct contact between air and the high-temperature heat transfer oil, thus ensuring the oil does not oxidize due to high temperatures and extending its service life. The high-level storage tank 4 is designed at the highest position of the extrusion granulator template preheating system 100, maintaining a liquid level of 1 / 2 to 2 / 3 during normal operation. The functions of the high-level storage tank 4 are: to accommodate the increase in heat transfer oil due to expansion, stabilize the pressure of the heat transfer oil within the system to ensure safe and stable system operation; and to add oil to the system or replenish the heat transfer oil lost due to evaporation and operation. During high-temperature operation, coking may occur in the heat transfer oil, affecting its heat transfer efficiency. The coked material needs to be cleaned promptly, which is achieved through the cleaning filter 7. During normal operation, the cross-line valve 9 of the filter 7 is closed, meaning the pipeline filter 7 is in operation. If the flow rate at the outlet flow meter 13 of the circulating pump 11 decreases, clean the filter 7 promptly. When inspecting the filter 7, first open the cross-line valve 9, and then close the first oil valve 6 and the second oil valve 8. This ensures the timely flow rate at the inlet of the circulating pump 11 and prevents the circulating pump 11 from running dry and being damaged. The electric heater 16 in the heating device 101 has a built-in temperature control function, which can automatically adjust the power of the electric heater 16 according to the temperature of the heat transfer oil, or the power of the electric heater 16 can be manually adjusted. The heating system is equipped with a safety valve 20 to protect against the risk of system overpressure. The template 27 has its own heating flow channel. Depending on the size of the template 27, the heating flow channel is generally 4 inlets and 4 outlets or 6 inlets and 6 outlets. This embodiment uses a 4 inlets and 4 outlets configuration. Based on the number of heating channels and connection dimensions of template 27, select high-temperature resistant metal hoses that match template 27. The number of metal hoses can be even or odd (depending on the template channels). These hoses are installed on template 27, allowing heat transfer oil to flow into template 27 via an even-numbered inlet / even-numbered outlet or odd-numbered inlet / odd-numbered outlet configuration. The metal hoses are designated as: first oil inlet pipe 22, second oil inlet pipe 23, third oil inlet pipe 24, fourth oil inlet pipe 25, first oil outlet pipe 29, second oil outlet pipe 30, third oil outlet pipe 31, and fourth oil outlet pipe 32. One end of the first oil inlet pipe 22, second oil inlet pipe 23, third oil inlet pipe 24, and fourth oil inlet pipe 25 is connected to the heat transfer oil supply line, and the other end is connected to template 27. One end of the first oil outlet pipe 29, second oil outlet pipe 30, third oil outlet pipe 31, and fourth oil outlet pipe 32 is connected to the return oil line, and the other end is connected to template 27. During heating, template 27 is covered with an insulation box to reduce heat loss and improve heating efficiency.

[0034] According to the second aspect of this application, such as Figure 2As shown, the embodiments of this application also propose a method for installing an extrusion granulator template. This method employs a preheating system for the extrusion granulator template as described in the above embodiments to heat the template to the installation temperature before installation. The method includes the following steps: S1, System Connection and Circulation Establishment: Connect the template using multiple inlet and outlet metal hoses, and start the oil supply and heating devices to establish a heat transfer oil circulation; S2, Segmented Heating and Temperature Control: Start the electric heater to heat the template in segments according to a preset temperature gradient, and maintain a constant temperature in each segment until the template temperature reaches the target installation temperature; S3, Oil Drainage and Disassembly: Stop heating, drain the heat transfer oil from the extrusion granulator template preheating system and the template, and disassemble the inlet and outlet metal hoses connected to the template; S4, Hot Installation: Hoist the template, preheated to the target temperature, to the die head housing position, and complete the installation using a bolt tightening method combining inside-out and symmetrical fastening.

[0035] Specifically, such as Figure 2 As shown, the present application provides a method for installing a template in an extrusion granulator, which includes the following steps: S1. System connection and circulation establishment steps: Connect the template with multiple inlet and outlet metal hoses, and start the oil supply device and heating device to establish heat transfer oil circulation. S2. Segmented heating and constant temperature steps: Start the electric heater to heat the template in segments according to the preset temperature gradient, and maintain a constant temperature in each segment until the template temperature reaches the target installation temperature. S3. Oil draining and disassembly steps: Stop heating, drain the heat transfer oil from the preheating system of the extrusion granulator template and inside the template, and disassemble the oil inlet and outlet metal hoses connected to the template. S4. Hot installation steps: Hoist the template, which has been preheated to the target temperature, to the position of the mold head housing, and complete the installation by using a bolt fastening method that combines inside-out and symmetrical fastening.

[0036] Specifically, such as Figure 2 As shown, in step S1, the operator secures the ends of the first, second, third, and fourth oil inlet pipes, as well as the ends of the first, second, third, and fourth oil outlet pipes, to the corresponding inlet and outlet ports on the template via flanges, and covers the template with an insulation box to reduce heat loss. Then, the main inlet valve, first oil valve, second oil valve, main outlet valve, supply valve, and return valve are opened sequentially, while the cross-line valve, connecting valve, vent valve, and drain valve are closed simultaneously. Next, heat transfer oil is added to the high-level storage tank to the specified level through the refueling valve, and the nitrogen valve is opened to nitrogen-seal the tank. Finally, the circulation pump is started, and the heat transfer oil begins to circulate within the system. At this time, the high-point vent valves (first vent valve and second vent valve) can be opened to remove residual gas from the pipeline, and then closed after the circulation stabilizes.

[0037] In step S2, the electric heater is started and its temperature controller is set to the initial target temperature (e.g., 50°C). The heat transfer oil is heated and flows through the internal channels of the template under the drive of the circulating pump. Monitoring with the temperature controller, once the temperature gauge on the template shows the current set temperature has been reached, this temperature is maintained for a period of time (e.g., 2 hours) to allow the template to be heated evenly and to initially release stress. Subsequently, the temperature controller setting is gradually increased (e.g., 75°C, 100°C) according to a set gradient (e.g., 25°C), and the heating and temperature-maintaining process is repeated at each new temperature point until the template temperature reaches the target installation temperature, consistent with the normal operating temperature of the extrusion granulator. This temperature is then maintained again to ensure a uniform and stable overall temperature field.

[0038] In step S3, first open the connecting valve, then close the oil supply valve and return valve, and stop the electric heater. The heat transfer oil then circulates naturally, and the system enters the natural cooling phase. Once the system temperature drops to a safe range, stop the circulation pump. Simultaneously, open the low-point drain valves (first and second drain valves) located at the lowest points of the pipeline to completely drain all heat transfer oil remaining in the metal hoses, connecting pipes, and the heating channels inside the template. After draining the oil, disassemble all connecting flanges between the metal hoses and the template, and remove the insulation box.

[0039] In step S4, workers, wearing heat-resistant clothing, use hoisting equipment to smoothly lift the preheated template (ensuring it is free of residual oil) to the installation position on the extrusion granulator die head housing. Then, two operators work together to install and tighten the bolts using a combination of inside-out and symmetrical tightening methods: First, the two operators work simultaneously, tightening all bolts on the inner side of the template's granulation belt to 50% of the target torque value in a symmetrical, alternating sequence; then, in the same manner, tighten all bolts on the outer side of the granulation belt to 50% of the target torque value. Finally, following the same inside-out sequence, all bolts are tightened to 100% of the target torque value. After tightening, the template installation is complete, and production can begin.

[0040] Thus, the extrusion granulator template installation method provided in this application, through independent and controllable system connection and segmented heating, firstly preheats the template to be installed to the working temperature precisely and evenly outside the machine, ensuring that its thermal expansion has fully occurred before installation; then, thorough oil drainage and cleaning disassembly prepare for safe hoisting; finally, using an inside-out, symmetrical, cross-sectional, and graded bolt tightening process, installation is completed under heat, ensuring that the template can continuously expand freely and evenly during the tightening process. The direct technical effect of this method is that it reduces the downtime replacement time of up to 48 hours required by the traditional "hot disassembly and cold installation" to about 2 hours, greatly improving production efficiency; at the same time, it eliminates the installation thermal stress caused by temperature difference at the source, avoids deformation or cracking of the template granulation belt, significantly extends the service life of the template, and greatly reduces the operating risks in high-temperature environments.

[0041] In some embodiments, optionally, such as Figure 2 As shown, the segmented heating and temperature control steps specifically include: setting the initial target heating temperature of the heat transfer oil to a first temperature value and maintaining the temperature for a first duration; then gradually increasing the target heating temperature at fixed temperature intervals and maintaining the temperature for a first duration at each temperature point until the final target installation temperature is reached.

[0042] Specifically, such as Figure 2 As shown, this segmented heating process is achieved through precise control of the electric heater by a temperature controller. During operation, the initial target heating temperature of the heat transfer oil is first set to a first temperature value (e.g., 50°C). Once the circulating heat transfer oil temperature reaches this set value, the system does not immediately continue heating; instead, it controls the electric heater to maintain this temperature for a first duration (e.g., 2 hours). After the first constant-temperature period ends, the system increases the target heating temperature to the next set value (e.g., 75°C) at fixed temperature intervals (e.g., 25°C) and maintains the same constant temperature for the same duration. This stepped "heating up, constant temperature" process is repeated cyclically, for example, successively set to 100°C, 125°C, etc., until the temperature of the heat transfer oil and the template reaches the final target installation temperature (e.g., above 200°C) that matches the normal operating conditions of the extrusion granulator, and is then maintained at this final temperature point. By using a multi-stage, gradual heating method, sufficient and uniform expansion time is provided for the template metal component, allowing the thermal stress inside and in the area in contact with the heating channel to be released gradually and fully at each temperature plateau period, thus avoiding instantaneous thermal stress concentration caused by rapid and violent heating.

[0043] In some embodiments, optionally, such as Figure 2 As shown, the first temperature value is 50℃, the fixed temperature interval is 25℃, and the first duration is 2 hours.

[0044] Specifically, such as Figure 2As shown, setting the first temperature value to 50℃, specifying the first duration of each constant temperature cycle as 2 hours, and setting a fixed temperature interval of 25℃ are key time windows, verified through extensive practice, sufficient for the template to complete sufficient and uniform expansion and release the corresponding stage of thermal stress under this temperature gradient. This allows operators to execute precisely, consistently achieving the goal of uniform and undamaged preheating of the template under all circumstances, ensuring the predictability and stability of the final installation quality, and effectively eliminating quality risks caused by improper operating parameters.

[0045] In some embodiments, optionally, such as Figure 3 As shown, in the hot installation step, the bolt tightening method combining inside-out and symmetrical tightening includes: first tightening the bolts on the inner side of the granulation belt of the template, and then tightening the bolts on the outer side of the granulation belt of the template; and when tightening the inner and outer bolts, a symmetrical and cross sequence is used for tightening; wherein, all bolts are first tightened to 50% of the target torque value, and then tightened to 100% of the target torque value.

[0046] Specifically, such as Figure 3As shown, in this step, the inner bolts (position sequence numbered A, B, C, D, E, F, G, H, I, J, K, L, a total of 12 positions) and the outer bolts (position sequence numbered M, N, O, P, Q, R, S, T, U, V, W, X, a total of 12 positions) surrounding the granulation belt on the template are first identified. During tightening, a strict "inside-out" sequence is followed, meaning all inner bolts are completely tightened before the outer bolts are tightened. When tightening the inner or outer bolts, a "symmetrical cross" sequence is used. For example, two operators work simultaneously; one tightens the bolt at position A while the other tightens the bolt at the symmetrical position B, and then positions C and D, E and F are tightened sequentially, ensuring that the tightening force is applied evenly and evenly in the circumferential direction. The entire tightening process is divided into two distinct stages: In the first stage, all bolts (inner and outer sides) are pre-tightened to 50% of the target torque value. The purpose of this stage is to initially position the template and eliminate most gaps. In the second stage, all bolts are finally tightened to 100% of the target torque value, following a sequence from the inside out. The technical principle of this method lies in controlling the sequence to ensure that the thermal expansion constraint of the template is gradually established from the inside out in a uniform and symmetrical manner during tightening. This avoids warping or uneven shear stress during expansion caused by localized or unilateral premature locking. The direct technical effect is that it ensures the template can freely and completely release its final thermal expansion after hot installation, thereby permanently guaranteeing the flatness of the granulation belt surface meets the standard. This fundamentally eliminates early wear or cracking caused by improper installation, greatly improving the installation success rate and the template's service life.

[0047] In practical applications, this application provides a method for installing a template in an extrusion granulator, which involves heating the template to be installed to the installation temperature before installation, and specifically includes the following steps: S501. Connect the template to be installed with a metal hose and put the oil supply device into operation to establish heat transfer oil circulation.

[0048] S502. Add heat transfer oil to the high-level storage tank and nitrogen seal the high-level storage tank.

[0049] S503. Establish heat transfer oil circulation, segmented heating of the template and constant temperature.

[0050] S504. Stop the heat transfer oil circulation heating, cool down and drain the oil.

[0051] S505. Install the template by combining the method of tightening bolts from the inside out and the method of tightening bolts symmetrically from top to bottom and left to right.

[0052] This installation method shortens the template replacement time, reducing it from 48 hours to 2 hours. During the template replacement process, the extruder does not need to be cooled down, saving maintenance time. It also reduces the risk of burns during template replacement and improves the production efficiency of the equipment.

[0053] Specifically, in this embodiment, S501 connects the template to be installed using a metal flexible hose and activates the oil supply device to establish heat transfer oil circulation, including: S601. Use four metal hoses as oil inlet pipes and another four metal hoses as oil outlet pipes to connect to the template through flanges, and cover the template with an insulation box.

[0054] S602. Open the main oil inlet valve, the first oil valve, and the second oil valve; close the cross-line valve; and put the filter and its circulating pump into operation.

[0055] S603. Open the main oil outlet valve, oil supply valve, and oil return valve; close the connecting valve, high-point vent valve, and low-point drain valve. The high-point vent valve includes a first vent valve and a second vent valve, both located at the highest point of the template. These are used to discharge oil vapors generated during the initial establishment of oil circulation, preventing prolonged contact between the heat transfer oil and air, and preventing oxidation and deterioration of the heat transfer oil as it gradually heats up. The low-point drain valve includes a first drain valve and a second drain valve. After stopping heating the template, both valves need to be opened to drain the heat transfer oil, facilitating template installation.

[0056] This process establishes a heat-conducting oil circulation between the first oil valve and the template, providing a continuous oil supply circulation system for the continuous heating of the template.

[0057] Specifically, in this embodiment, S502 involves adding heat transfer oil to the high-level storage tank and nitrogen-sealing the high-level storage tank, including: S701. Put the circulating pump into operation using the first pressure gauge, the second pressure gauge, and the flow meter. The first pressure gauge is installed on the pipeline between the circulating pump inlet and the second oil valve, while the second pressure gauge and the flow meter are both installed on the pipeline between the second check valve and the main outlet valve.

[0058] S702. Open the refueling valve of the high-level storage tank, add heat transfer oil through the refueling valve, and then close the refueling valve after the liquid level of the high-level storage tank reaches 2 / 3.

[0059] S703. Open the nitrogen valve and activate the first check valve to nitrogen-seal the high-level storage tank. Nitrogen-sealing the high-level storage tank means that after filling the high-level storage tank with nitrogen, it isolates the direct contact between air and heat transfer oil.

[0060] By introducing nitrogen into the high-level storage tank to seal the heat transfer oil, the heat transfer oil is isolated from the air. During continuous operation in the oil circulation system, it not only provides continuous heat to the template, but also extends the service life of the heat transfer oil.

[0061] Specifically, in this embodiment, S503 establishes a heat transfer oil circulation, heats the template in sections and maintains a constant temperature, including: S801. Start the circulation pump to allow the heat transfer oil to circulate between the oil supply device and the template. At the same time, open the high-point exhaust valve, that is, open the first exhaust valve and the second exhaust valve simultaneously to remove the oil and gas generated during the circulation process.

[0062] S802. Start the electric heater and activate the temperature controller of the electric heater. The initial setting of the temperature controller is set to 50℃.

[0063] S803. After the heat transfer oil temperature is heated to 50℃ and kept constant for 2 hours, set the temperature controller setting to 75℃.

[0064] S804. After the heat transfer oil temperature is heated to 75℃ and kept constant for 2 hours, set the temperature controller setting to 100℃.

[0065] S805, and similarly steps S803 to S804, increase the temperature controller setting value in a 25°C gradient until the heat transfer oil temperature reaches the current setting value and remains constant for 2 hours.

[0066] S806, The temperature gauge of the template is set to the final target value and kept at a constant temperature for 2 hours.

[0067] The heat transfer oil utilizes electrical energy to perform segmented, continuous, and constant-temperature heating of the template within an oil circulation system, raising it to the required installation temperature. The heat transfer oil has a high heat transfer coefficient, enabling high operating temperatures at relatively low pressures, with a maximum temperature reaching 350℃ and an operating pressure not exceeding 1MPa. The heat transfer oil also possesses high solubility, reducing sediment formation and providing comprehensive protection for various equipment systems.

[0068] Specifically, in this embodiment, S504 stops the heat transfer oil circulation heating, cools down and drains the oil, including: S901. Open the connecting valve, close the oil supply valve and the oil return valve, stop the electric heater, and stop the circulating pump after the heat transfer oil cools down to room temperature.

[0069] S902. Open the low-point drain valve to drain the heat transfer oil from the metal hose and the internal flow channel of the template.

[0070] After heating is completed, the circulating pump and electric heater are stopped through the above process, thus stopping the heating of the template. The heat transfer oil is discharged to facilitate the installation of the template.

[0071] Specifically, in this embodiment, S505 installs the template by combining an inside-out bolt tightening method and a top-bottom and left-right symmetrical bolt tightening method, including: S1001. Disconnect all metal hoses from the flanges connecting them to the template to be installed, and remove the insulation box from the surface of the template.

[0072] S1002. The operator puts on heat-resistant clothing and hoists the template to be installed to the position of the mold head shell.

[0073] S1003. Two people work together to tighten the template bolts simultaneously. The bolts are tightened by tightening them from the inside out. First, tighten the bolts on the inside of the template granulation belt, and then tighten the bolts on the outside of the template granulation belt.

[0074] S1004. Use the symmetrical bolt tightening method (top, bottom, left, and right) to tighten the bolts on the inner side of the template granulation belt. First, tighten all bolts to 50% of the target torque value.

[0075] S1005. Use the symmetrical bolt tightening method (top, bottom, left, and right) to tighten the bolts on the outside of the template granulation belt. First, tighten all bolts to 50% of the target torque value.

[0076] S1006. Tighten the bolts a second time according to the target torque value. First tighten the bolts on the inside of the template granulation belt, then tighten the bolts on the outside of the template granulation belt.

[0077] S1007. After all bolts are tightened, the template is put into use.

[0078] After the template is installed through this process, it can expand freely, all thermal expansion stress is released, and the surface flatness of the granulation belt permanently meets the standard.

[0079] In the description of this application, the term "multiple" refers to two or more. Unless otherwise expressly defined, the terms "upper," "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The terms "connection," "installation," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0080] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0081] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An extrusion pelletizer die plate preheating system characterized by, The application relates to a heating device for a formwork, which comprises: a heating device arranged on the outlet pipeline of the circulating pump for circulating and heating the heat conducting oil to the formwork to be installed; an oil supply device connected with the oil pipeline of the heating device for supplying and recovering the heat conducting oil to the heating device; a nitrogen sealing device arranged on the nitrogen pipeline of the oil supply device and connected with the oil inlet end of the oil supply device through a pipeline for sealing and isolating the direct contact between air and the heat conducting oil by filling nitrogen; wherein the heating device comprises: a plurality of oil inlet metal hoses and a plurality of oil outlet metal hoses, the plurality of oil inlet metal hoses and the plurality of oil outlet metal hoses are connected with the heating flow channel of the formwork through flanges for leading in and leading out the heat conducting oil to heat the formwork; an electric heater arranged on the oil inlet pipeline of the plurality of oil inlet metal hoses, and the oil outlet pipeline of the electric heater is connected with the plurality of oil inlet metal hoses through flanges; an oil supply valve arranged on the oil outlet pipeline of the electric heater and connected with the plurality of oil inlet metal hoses for conveying the heated heat conducting oil; an oil return valve arranged on the oil return pipeline of the plurality of oil outlet metal hoses and connected with the oil supply device through a pipeline for returning the heat exchanged heat conducting oil to the oil supply device; a communication valve arranged between the outlet of the electric heater and the oil supply device.

2. The extrusion prilling die preheating system of claim 1, wherein, The heating device further comprises: a first liquid discharge valve arranged on the pipeline of the oil inlet metal hose and a second liquid discharge valve arranged on the pipeline of the oil outlet metal hose for discharging the heat conducting oil in the pipeline of the oil inlet metal hose, the pipeline of the oil outlet metal hose and the heating flow channel of the formwork after heating is completed; a first gas discharge valve arranged on the gas discharge pipeline of the oil inlet metal hose and a second gas discharge valve arranged on the gas discharge pipeline of the oil outlet metal hose for discharging the oil gas in the oil inlet metal hose and the oil outlet metal hose when the heat conducting oil circulation is established.

3. The extrusion prilling die preheating system of claim 1, wherein, The oil supply device comprises: a high-level storage tank connected with the nitrogen sealing device through a nitrogen pipeline, which is internally used for storing the heat conducting oil and maintaining a nitrogen atmosphere; an oil filling valve arranged on the high-level storage tank for initially filling or supplementing the heat conducting oil; an oil inlet total valve arranged on the oil outlet pipeline of the high-level storage tank; a filter connected with the high-level storage tank through a first oil valve and a second oil valve which are connected in series on the outlet pipeline of the oil inlet total valve; a circulating pump arranged on the outlet pipeline of the second oil valve for driving the heat conducting oil circulation, and a second check valve, a flow meter and a second pressure gauge are sequentially connected in series on the oil outlet pipeline of the circulating pump; a first pressure gauge mounted on the inlet pipeline of the circulating pump for monitoring the pump inlet pressure; an oil outlet total valve connected in series on the oil outlet pipeline of the circulating pump and connected with the inlet pipeline of the electric heater.

4. The extrusion prilling die preheating system of claim 3, wherein, The oil supply device further comprises: a cross valve, one end of the cross valve is connected with the inlet pipeline of the first oil valve, and the other end of the cross valve is connected with the outlet pipeline of the second oil valve.

5. The extrusion prilling die preheating system of claim 3, wherein, The nitrogen sealing device comprises: a first check valve connected with the nitrogen pipeline leading to the high-level storage tank. A nitrogen valve, whose inlet is connected with the outlet pipeline of the first check valve, and whose outlet is connected with the pipeline of the high-level storage tank.

6. The extrusion prilling die preheating system of claim 1, wherein, The plurality of oil inlet metal hoses include a first oil inlet pipe, a second oil inlet pipe, a third oil inlet pipe, and a fourth oil inlet pipe. The plurality of oil outlet metal hoses include a first oil outlet pipe, a second oil outlet pipe, a third oil outlet pipe, and a fourth oil outlet pipe.

7. A method of installing a die plate in an extrusion pelletizer, characterized by, The extrusion granulator template preheating system according to any one of claims 1 to 6 is used to heat the template to be installed to the installation temperature, and then install it, comprising the following steps: S1, system connection and circulation establishment step: connecting the template with the plurality of oil inlet metal hoses and the plurality of oil outlet metal hoses, and starting the oil supply device and the heating device to establish the circulation of the heat conducting oil; S2, segmented heating and constant temperature step: starting the electric heater to heat the template in segments with a preset temperature gradient, and keeping constant temperature at each temperature segment until the temperature of the template reaches the target installation temperature; S3, oil discharge and disassembly step: stopping heating, discharging the heat conducting oil inside the extrusion granulator template preheating system and the template, and disassembling the oil inlet metal hoses and the oil outlet metal hoses connected with the template; S4, hot installation step: hoisting the template preheated to the target temperature to the position of the die shell, and completing the installation by using the bolt fastening method combining inside-out and symmetric fastening.

8. The extrusion pelletizer die plate installation method according to claim 7, wherein The segmented heating and constant temperature step specifically comprises: setting the initial heating target temperature of the heat conducting oil as a first temperature value, and keeping constant temperature for a first time length; then gradually increasing the heating target temperature at a fixed temperature interval, and keeping constant temperature at each temperature point for the first time length until reaching the final target installation temperature.

9. The extrusion pelletizer die plate installation method according to claim 8, wherein The first temperature value is 50℃, the fixed temperature interval is 25℃, and the first time length is 2 hours.

10. The method of claim 7, wherein, In the hot installation step, the bolt fastening method combining inside-out and symmetric fastening comprises: first fastening the bolts on the inner side of the granulation belt of the template, and then fastening the bolts on the outer side of the granulation belt of the template; and when fastening the inner side bolts and the outer side bolts, both are fastened in a symmetric cross sequence; wherein, first fastening all the bolts at 50% of the target torque value for the first time, and then fastening them at 100% of the target torque value for the second time.

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