Safety protection device for polyester melt discharge

Abstract

The utility model discloses a safety protection device for polyester melt discharge. The safety protection device comprises a protection pipeline, a heating medium jacket pipe, a melt receiving trolley and a DCS (Distributed Control System), the protective pipeline is connected through a sectional flange, the outer wall is coated with a heat insulation layer, and the end is provided with a lug and a guide block. The heating medium jacketed pipe is nested on the outer side of the protective pipeline, a heating medium inlet is formed in the top, an outlet is formed in the bottom, the jacketed inner pipe and the jacketed outer pipe form an annular cavity, melt is guided through heating medium circulation, and the temperature is controlled. And the melt receiving trolley is arranged below the tail end of the protective pipeline and is used for receiving and discharging the melt. And the DCS system is linked with the melt discharge valve, so that delayed opening and closing of the heating medium switch valve are realized, and full-process automation of melt discharge is ensured. The problems that a traditional device is prone to being blocked, high in scalding risk and high in maintenance cost are solved through the technologies of active flow guiding and blocking prevention of a heating medium, rapid disassembly and assembly of segmented flanges, DCS accurate regulation and control and the like.

Description

Technical Field

[0001] This utility model relates to the field of polyester chip production technology, specifically to a safety protection device for polyester melt discharge. Background Technology

[0002] In the production of polyester chips, melt discharge is one of the key processes. In the existing technology, the safety protection of melt discharge usually adopts a single long pipe structure to draw out the high-temperature melt (200-300°C) from the melt valve at the front end of the pelletizer and discharge it to the receiving device.

[0003] However, this structure has the following prominent problems in practical applications: The long pipe has a large exposed area, making it easy for the high-temperature molten metal to adhere to the inner wall and gradually solidify, leading to a reduction in the pipe's flow cross-section or even complete blockage, forcing production to be interrupted for cleaning and severely impacting production efficiency. Simultaneously, the continuously high temperature of the molten metal causes the pipe wall temperature to rise, especially when the equipment is located on the third floor or higher. The long pipe has low heat dissipation efficiency, and the outer wall temperature can reach over 80°C, easily causing accidental burns to operators. Furthermore, pipe blockage requires manual cleaning after shutdown, and frequent disassembly and maintenance can lead to flange seal failure, pipe deformation, and other problems, further increasing equipment maintenance costs. In addition, traditional pipes lack active flow guidance design, and when relying on gravity discharge, they are easily affected by fluctuations in molten metal viscosity, leading to poor discharge or the risk of splashing. While existing technologies have attempted to improve these problems by adding insulation layers or local cooling devices, they have failed to fundamentally solve the contradiction of heat transfer between the molten metal and the pipe wall, and the increased structural complexity leads to a higher failure rate.

[0004] Therefore, there is an urgent need for a new type of protective device that can effectively suppress melt adhesion and ensure safe discharge over long distances. Utility Model Content

[0005] The purpose of this utility model is to provide a safety protection device for polyester melt discharge. Through the active flow guidance design of the heat medium jacket pipe, the high-temperature melt does not come into contact with the inner wall of the protective pipe during the discharge process, completely solving the blockage problem caused by melt adhesion and solidification, and ensuring smooth discharge over long distances. The segmented flange connection combined with the wear-resistant coating enables quick disassembly and corrosion protection, significantly reducing maintenance costs. The delayed linkage control of the DCS system and the melt discharge valve, combined with the precise adjustment of the heat medium switching valve, realizes fully automated monitoring of melt discharge, eliminates the risk of human error, and provides a safe, efficient, and low-consumption melt discharge solution for polyester production.

[0006] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: A safety protection device for polyester melt discharge includes a protective pipe, a heat transfer medium jacket pipe, a melt receiving trolley and a DCS system; the protective pipe is connected in sections through protective pipe connecting flanges; the outer wall of the protective pipe is covered with a protective pipe insulation layer; the pipe end of the protective pipe is provided with a protective pipe lug and a protective pipe guide block;

[0007] The heat medium jacketed pipe is nested outside the protective pipe; the top of the heat medium jacketed pipe is provided with a heat medium inlet; the bottom of the heat medium jacketed pipe is provided with a heat medium outlet;

[0008] The melt receiving trolley is located below the end of the protective pipe; the melt receiving trolley is used to receive the discharged polyester melt.

[0009] As a preferred embodiment of a safety protection device for polyester melt discharge, the heat medium jacketed pipe is fixed to a concrete beam by a jacketed pipe support and a jacketed pipe guide frame; the concrete beam is located at the end of the protective pipe; the jacketed pipe guide frame is used in conjunction with the protective pipe guide block to facilitate the installation of the heat medium jacketed pipe.

[0010] As a preferred embodiment of a safety protection device for polyester melt discharge, the heat transfer medium jacket pipe includes an inner jacket pipe and an outer jacket pipe; the inner jacket pipe and the outer jacket pipe are formed by welding the heat transfer medium jacket pipe.

[0011] As a preferred embodiment of a safety protection device for polyester melt discharge, a heat medium switching valve is provided on the heat medium jacket pipe; the heat medium switching valve is used to control the flow of heat medium into the heat medium jacket pipe.

[0012] As a preferred embodiment of a safety protection device for polyester melt discharge, the heat transfer medium switching valve is connected to the melt discharge valve via the DCS system; the DCS system is used to transmit the switching signal of the melt discharge valve to the heat transfer medium switching valve.

[0013] As a preferred embodiment of a safety protection device for polyester melt discharge, the protective pipeline is provided with an inspection door (10); the inspection door is used for maintenance of the protective pipeline.

[0014] The beneficial effects of this utility model are as follows:

[0015] First, improved anti-clogging performance. The heat transfer medium jacketed pipe actively guides the flow so that the molten material does not come into contact with the inner wall of the protective pipe, completely avoiding clogging problems caused by molten material adhesion and solidification, and ensuring smooth discharge over long distances.

[0016] Second, safety risks are reduced. The temperature of the outer wall of the protective pipeline is controlled below 50℃, eliminating the risk of burns from high temperatures; the melt discharge valve and the heat medium switching valve are linked and controlled by a DCS system to achieve automated opening and closing, reducing the risk of human error.

[0017] Third, improved ease of maintenance. The segmented flange connection, combined with the wear-resistant coating design, enables quick assembly and disassembly as well as corrosion protection. The access door facilitates cleaning of the pipeline interior, reducing equipment maintenance costs by more than 60%.

[0018] Fourth, enhanced flow guiding efficiency. The heat medium circulation in the jacketed inner tube forms a stable temperature field, and combined with the spiral flow guiding groove design on the inner wall of the protective pipe, the melt discharge efficiency is improved by 40%, and splashing problems caused by viscosity fluctuations are avoided.

[0019] Fifth, structural reliability is improved. The jacketed pipe support and guide frame are fixed together, and the protective pipe guide block is used for precise positioning, effectively resisting the effects of vibration and thermal expansion, reducing the equipment failure rate by 70%.

[0020] Sixth, optimized energy utilization: The heat transfer medium circulation system recovers waste heat, reduces heat loss, and has a significant energy-saving effect. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0022] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0023] Figure 1 This is a schematic diagram of the structure of a polyester melt discharge safety protection device provided in an embodiment of this utility model.

[0024] In the diagram, 1. Protective pipe; 2. Jacketed pipe guide frame; 3. Protective pipe insulation layer; 4. Protective pipe lug; 5. Jacketed pipe support; 6. Protective pipe connecting flange; 7. Heat medium jacketed pipe; 8. Protective pipe guide block; 9. Heat medium switch valve; 10. Inspection door; 11. Melt receiving trolley; 12. Concrete beam; 13. DCS system; 14. Melt discharge valve. Detailed Implementation

[0025] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0027] See Figure 1 This utility model provides a safety protection device for polyester melt discharge, including a protective pipe 1, a heat medium jacketed pipe 7, a melt receiving trolley 11 and a DCS system 13; the protective pipe 1 is connected in sections by protective pipe connecting flanges 6; the outer wall of the protective pipe 1 is covered with a protective pipe insulation layer 3; the pipe end of the protective pipe 1 is provided with a protective pipe lug 4 and a protective pipe guide block 8;

[0028] Specifically, the protective pipe 1 adopts a segmented flange connection (6), which facilitates transportation, installation and subsequent maintenance. The segmented structure allows for the prefabrication of individual pipe segments in the factory and rapid on-site assembly, shortening the construction period; the flange connection has strong sealing performance and can withstand high temperature and high pressure conditions. The insulation layer 3 of the protective pipe (such as ceramic fiber or aerogel) blocks the high temperature of the melt from being conducted outward, reducing the outer wall temperature (measured ≤50℃) and preventing the risk of burns. The protective pipe lug 4 is welded to the concrete beam 12 through embedded parts, and works with the limiting block 8 (L-shaped stainless steel component) to fix the axial position of the pipe and prevent displacement caused by thermal expansion; the protective pipe guide block 8 is fixed to the flange connection by bolts to adjust the docking angle of the segmented pipes and ensure that the coaxiality error is <2mm.

[0029] The heat medium jacketed pipe 7 is nested outside the protective pipe 1; the top of the heat medium jacketed pipe 7 is provided with a heat medium inlet; the bottom of the heat medium jacketed pipe 7 is provided with a heat medium outlet;

[0030] Specifically, the heat transfer medium jacketed pipe 7 adopts a double-layered structure, forming a closed annular cavity between the inner and outer jacketed pipes. The heat transfer medium (such as heat transfer oil or saturated steam) is injected from the top heat transfer medium inlet, flows downwards along the annular channel between the inner and outer jacketed pipes, and finally exits from the bottom heat transfer medium outlet. This design ensures full contact between the heat transfer medium and the outer wall of the protective pipe 1, maintaining the melt temperature stably within the range of 280-320℃ through heat conduction. When the melt is discharged, the circulating flow of the heat transfer medium continuously carries away the heat released by the melt, preventing a sharp increase in melt viscosity due to temperature drop and avoiding direct contact between the high-temperature melt and the inner wall of the protective pipe, which could lead to adhesion and solidification. The outer wall of the jacketed pipe is polished (Ra≤0.8μm) and coated with a polytetrafluoroethylene coating to further reduce the flow resistance of the heat transfer medium and inhibit coking.

[0031] The melt receiving trolley 11 is located below the end of the protective pipe 1; the melt receiving trolley 11 is used to receive the discharged polyester melt.

[0032] Specifically, the melt receiving trolley 11 is a movable, corrosion-resistant metal container equipped with casters and a parking brake at the bottom, and its top opening faces the end of the protective pipe 1. When the melt discharge valve is opened, the high-temperature melt falls vertically into the melt receiving trolley 11 along the flow path of the heat medium jacket pipe. The trolley adopts a layered structure design: the bottom layer is a high-temperature alloy steel base, the middle layer is filled with a ceramic fiber insulation layer, and the surface layer is a stainless steel receiving tray. The receiving tray has an inclination angle of ≥15° and is equipped with guide grooves at the edges to ensure that the melt quickly gathers and is transferred to the subsequent processing section through the bottom drain port. The receiving trolley is also equipped with a weighing sensor and a liquid level monitoring device. When the melt weight is ≥50kg or the liquid level reaches the warning line, the DCS system automatically triggers an audible and visual alarm and locks the melt discharge valve to prevent excessive overflow and safety accidents.

[0033] In one possible embodiment, the heat medium jacketed pipe 7 is fixed to the concrete beam 12 by the jacketed pipe support 5 and the jacketed pipe guide frame 2; the concrete beam 12 is located at the pipe end of the protective pipe 1; the jacketed pipe guide frame 2 is used in conjunction with the protective pipe guide block 8 to facilitate the installation of the heat medium jacketed pipe 7.

[0034] Specifically, the heat medium jacketed pipe 7 is fixed to the concrete beam 12 in conjunction with the jacketed pipe support 5 (H-beam welded component) and the jacketed pipe guide frame 2 (adjustable angle slide rail), forming a rigid support system. During installation, the V-shaped groove of the jacketed pipe guide frame 2 engages with the boss of the protective pipe guide block 8. By adjusting the horizontal / vertical angle of the jacketed pipe guide frame 2 (±5° adjustable), the coaxiality of the heat medium jacketed pipe 7 and the protective pipe 1 is calibrated, ensuring that the heat medium circulation flow path is consistent with the melt discharge direction, maximizing the flow guiding efficiency.

[0035] In one possible embodiment, the heat medium jacketed pipe 7 includes an inner jacketed pipe and an outer jacketed pipe; the inner jacketed pipe and the outer jacketed pipe are formed by welding the heat medium jacketed pipe 7.

[0036] Specifically, the heat transfer medium jacket pipe 7 is welded together with the inner jacket pipe (heat transfer oil channel) and the outer jacket pipe (protective shell), and the double-layer structure has a pressure resistance rating of 10MPa.

[0037] The inner jacket tube is made of 316L stainless steel seamless pipe (8mm wall thickness), with the outer wall polished to Ra≤0.4μm to reduce the flow resistance of the heat transfer medium. The outer jacket tube is made of Q235B carbon steel pipe (10mm wall thickness), with both the inner and outer walls coated with polytetrafluoroethylene (PTFE) (0.5mm thickness), providing both corrosion resistance and wear resistance. Welding is performed using a fully automated argon arc welding process, and the weld seams are 100% radiographically inspected to ensure the jacket's sealing performance. The heat transfer medium (heat transfer oil or saturated steam) circulates within the annular cavity formed by the inner and outer jacket tubes, maintaining the melt temperature at 280-320℃ through heat conduction to prevent a sharp increase in melt viscosity and a decrease in fluidity due to temperature drops.

[0038] In one possible embodiment, a heat medium switching valve 9 is provided on the heat medium jacket pipe 7; the heat medium switching valve 9 is used to control the flow of heat medium into the heat medium jacket pipe 7.

[0039] Specifically, the heat medium switching valve 9 is a double-gate pneumatic shut-off valve (DN100 diameter), with the valve core made of Stellite alloy through welding, resistant to high-temperature erosion. The valve and the heat medium pipeline are connected by a compression fitting, with a response time of <0.5s. When the melt discharge valve 14 opens, the DCS system 13 simultaneously sends a signal to trigger the heat medium switching valve 9 to fully open, and the heat medium circulates at a flow rate of 2.5m / s; when the discharge is complete, the valve closes after a 30-second delay, utilizing residual heat to dry any remaining melt in the pipeline and prevent solidification and blockage. The valve is equipped with a valve position feedback device to monitor the opening status in real time and upload the data to the DCS system.

[0040] In one possible embodiment, the heat transfer medium switching valve 9 is signal-connected to the melt discharge valve 14 via the DCS system 13; the DCS system 13 is used to transmit the switching signal of the melt discharge valve 14 to the heat transfer medium switching valve 9.

[0041] Specifically, the DCS system 13 is equipped with redundant PLC controllers, and the switching signal of the melt discharge valve 14 is transmitted to the DCS in real time via hard-wired connection (Profibus-DP protocol). The logic controller has a built-in timing control program: when the melt discharge valve 14 is opened, the heat transfer medium switching valve 9 is activated after a 2-second delay to avoid instantaneous thermal shock; when closed, the hysteresis closing time of the heat transfer medium valve can be dynamically adjusted according to the melt viscosity (extended to 60 seconds when viscosity > 500 Pa·s). The system is equipped with over-temperature (>350℃) and over-pressure (>0.8MPa) alarm interlocks, which, when triggered, immediately cut off the heat transfer medium supply and open the emergency vent valve.

[0042] In one possible embodiment, the protective pipe 1 is provided with an inspection door 10; the inspection door 10 is used for inspecting and maintaining the protective pipe 1.

[0043] Specifically, the inspection door 10 is a quick-opening blind flange structure (ANSI Class 150), equipped with double metal sealing rings and pneumatic struts. The door body is embedded in the flange connection of the protective pipe 1, with an opening angle ≥120°, and is equipped with an LED anti-glare light and an observation window (tempered borosilicate glass, temperature resistant to 800℃). During maintenance, operators can use the inspection door to clean coking deposits on the inner wall of the pipe or replace the wear-resistant coating (ceramic spraying repair). The door hinge uses a self-lubricating bearing, with an opening and closing torque <20 N·m, allowing for quick inspection of the pipeline's operating status during routine checks.

[0044] The working principle of this utility model is as follows:

[0045] First, the melt discharge start-up stage: When the pelletizer malfunctions or stops, the melt discharge valve 14 opens upon receiving a command from the DCS system 13. The melt flows from the front valve of the pelletizer through the protective pipe 1 into the heat medium jacket pipe 7. The DCS system simultaneously triggers the heat medium switching valve 9 to fully open, and the heat transfer oil / steam is injected into the inner pipe of the jacket from the heat medium inlet, flowing downwards along the annular cavity. Through heat conduction, the melt temperature is stabilized in the range of 280-320℃ to prevent a sharp increase in viscosity due to temperature drop.

[0046] Second, the active flow guidance and anti-clogging mechanism: The outer wall of the heat transfer medium jacket pipe 7 is polished to Ra≤0.8μm and coated with polytetrafluoroethylene to reduce the probability of melt adhesion; the closed cavity formed by the inner and outer pipes of the jacket ensures that the heat transfer medium uniformly wraps the outer wall of the protective pipe 1, forming a dynamic temperature field. Under the heating action of the heat transfer medium, the melt maintains liquid fluidity and flows downward along the spiral guide groove (3-5mm deep) on the inner wall of the protective pipe, completely avoiding the risk of adhesion and solidification.

[0047] Third, the DCS system intelligently controls the system: The DCS system monitors the status of the melt discharge valve 14 in real time and controls the opening and closing of the heat transfer medium switch valve 9 through a time-delay relay; opening delay: the heat transfer medium switch valve 9 is activated 2 seconds after the melt valve opens to avoid instantaneous temperature difference shocks; closing delay: the heat transfer medium switch valve 9 is closed 30 seconds after the melt valve closes, utilizing residual heat to dry the residual melt in the pipeline. The system is equipped with over-temperature (>350℃) and over-pressure (>0.8MPa) interlock protection, and in case of abnormalities, the heat transfer medium is cut off and the emergency vent valve is opened.

[0048] Fourth, melt receiving and safety protection: After being guided by the heat transfer medium jacket pipe, the melt falls vertically into the melt receiving trolley 11 below the end. The melt receiving trolley 11 adopts a layered structure (base + insulation layer + stainless steel receiving tray), and has an internal guide channel to guide the rapid transfer of the melt. The melt receiving trolley 11 is equipped with a weighing sensor and a liquid level monitoring device. When the melt weight is ≥50kg or the liquid level reaches the warning value, the DCS triggers an audible and visual alarm and locks the discharge valve.

[0049] Fifth, maintenance and repair guarantee: The segmented flange connection of the protective pipeline 1 supports quick disassembly and assembly. The inspection door 10 is embedded in the flange interface and equipped with a self-lubricating bearing door shaft (opening and closing torque <20N·m), which facilitates cleaning of pipeline coking or replacement of wear-resistant coating. The jacketed pipe guide bracket 2 cooperates with the protective pipeline guide block 8 to ensure that the coaxiality error of long-distance pipeline is <2mm, avoiding displacement caused by vibration or thermal expansion.

[0050] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A safety protection device for polyester melt discharge, characterized in that, It includes a protective pipe (1), a heat medium jacketed pipe (7), a melt receiving trolley (11), and a DCS system (13); the protective pipe (1) is connected in sections through protective pipe connecting flanges (6); the outer wall of the protective pipe (1) is covered with a protective pipe insulation layer (3); the pipe ends of the protective pipe (1) are provided with protective pipe lugs (4) and protective pipe guide blocks (8); The heat medium jacketed pipe (7) is nested outside the protective pipe (1); the top of the heat medium jacketed pipe (7) is provided with a heat medium inlet; the bottom of the heat medium jacketed pipe (7) is provided with a heat medium outlet; The melt receiving trolley (11) is located below the end of the protective pipe (1); the melt receiving trolley (11) is used to receive the discharged polyester melt.

2. The polyester melt discharge safety protection device according to claim 1, characterized in that, The heat medium jacketed pipe (7) is fixed to the concrete beam (12) by the jacketed pipe bracket (5) and the jacketed pipe guide frame (2); the concrete beam (12) is set at the pipe end of the protective pipe (1); the jacketed pipe guide frame (2) is used in conjunction with the protective pipe guide block (8) to facilitate the installation of the heat medium jacketed pipe (7).

3. The polyester melt discharge safety protection device according to claim 1, characterized in that, The heat medium jacketed pipe (7) includes an inner jacketed pipe and an outer jacketed pipe; the inner jacketed pipe and the outer jacketed pipe are welded together to form the heat medium jacketed pipe (7).

4. The polyester melt discharge safety protection device according to claim 1, characterized in that, The heat medium jacket pipe (7) is equipped with a heat medium switch valve (9); the heat medium switch valve (9) is used to control the flow of heat medium into the heat medium jacket pipe (7).

5. A safety protection device for polyester melt discharge according to claim 4, characterized in that, The heat transfer switch valve (9) is connected to the melt discharge valve (14) via the DCS system (13); the DCS system (13) is used to transmit the switching signal of the melt discharge valve (14) to the heat transfer switch valve (9).

6. The polyester melt discharge safety protection device according to claim 1, characterized in that, The protective pipe (1) is provided with an inspection door (10); the inspection door (10) is used to inspect the protective pipe (1).

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