A heating jacket for a slurry line in polyester production
By designing the spiral fins and annular flow channel structure of the heating jacket in polyester production, the steam path and heat transfer area are optimized, solving the problems of uneven heating and esterification steam blockage, and achieving a highly efficient and energy-saving slurry heating effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG WANKAI NEW MATERIAL
- Filing Date
- 2025-06-30
- Publication Date
- 2026-06-05
AI Technical Summary
Existing heating jackets suffer from slow heating, uneven steam distribution, low steam utilization, and easy blockage of esterification steam, which affect the efficiency and quality of polyester production.
Design a heating jacket for polyester production, with spiral fins and annular flow channels on the outside of the inner tube, steam inlet at the top and outlet at the bottom, the height of the spiral fins gradually increasing, combined with a condenser and insulation layer to optimize the steam path and heat transfer area, and prevent condensation of impurities in esterification steam.
This method achieves efficient and uniform heating of the slurry, reduces steam blockage, improves steam utilization, lowers production costs and energy consumption, and responds to the energy conservation and emission reduction policy.
Smart Images
Figure CN224326865U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of polyester production technology, specifically relating to a heating jacket for slurry pipelines in polyester production. Background Technology
[0002] In polyester production, slurry temperature control is crucial for product quality and production efficiency. The polyester production process requires raising the slurry from its initial temperature to a specific temperature to meet the requirements of subsequent reactions or processing. Slurry at too low a temperature is prone to clogging in the conveying pipelines, affecting the continuity of the equipment, and also causes drastic temperature changes in the reaction environment after entering the reaction unit, which is detrimental to the normal progress of the reaction. Without effective heating methods, relying solely on ambient temperature or the limited residual heat of the equipment itself results in a slow and difficult-to-precise temperature rise of the slurry, severely impacting production efficiency and the stability of product quality.
[0003] Currently, slurry preheating can be achieved through centralized heating and pipeline heating. For example, patent CN211729719U discloses a steam-heated slurry system and slurry processing system. This system uses steam heating pipes installed inside the slurry tank to heat and maintain the temperature of the slurry. However, slurry heated in this way still cools down during transport. When the transport pipeline is long, it is difficult to control the temperature of the slurry entering the reaction device, and the equipment has a large footprint and high modification costs. Currently, converting ordinary pipelines into jacketed pipes is a common heating method. For example, patent CN214808463U discloses a heating jacket for a scraped film evaporator. The jacket uses spiral grooves as steam transport pipes to heat the inner pipe. However, in practice, polyester production companies often use esterification steam as a heat source. In this case, the spiral grooves in this technology are prone to accumulating impurities from the esterification steam, causing reduced jacket heating efficiency or even blockage. Therefore, there is an urgent need to find a heating jacket that can efficiently utilize both ordinary steam and esterification steam. Utility Model Content
[0004] This invention aims to overcome the shortcomings of existing heating jackets, such as slow heating, uneven internal steam distribution, low steam utilization, and easy blockage when using esterification steam. It proposes a heating jacket for slurry pipelines in polyester production to overcome the above-mentioned defects.
[0005] To achieve the above objectives, this utility model is implemented through the following technical solution:
[0006] A heating jacket for a slurry pipeline in polyester production includes an inner tube for conveying slurry and an outer tube sleeved outside the inner tube, such that a heating space for containing steam is formed between the inner tube and the outer tube.
[0007] The outer tube has a steam inlet at one end and a steam outlet at the other end, so that steam flows from the steam inlet through the heating space to the steam outlet;
[0008] The inner tube is provided with spiral fins with the inner tube as the axis;
[0009] The height of the spiral fins is less than the distance between the inner and outer tubes, thereby forming an annular flow channel that allows steam to pass directly through the heating space.
[0010] Common heating jackets typically consist of an inner tube for conveying fluid and an outer tube fitted over the inner tube. High-temperature steam flows in the gap between the inner and outer tubes, thereby heating the fluid. In polyester production, it is often necessary to heat the raw material slurry, such as dimethyl terephthalate and ethylene glycol. Heating these slurries requires careful consideration of heating efficiency. Traditional heating jackets usually have a smooth alloy inner tube, resulting in a small contact area between the steam and the inner tube and low heat exchange efficiency. Secondly, the uniformity of heating must be considered. Generally, the temperature is high at the steam inlet of the jacket, but decreases significantly as heat exchange progresses, leading to large temperature variations in the slurry during transport. This not only easily causes localized coking and blockage at high temperatures but also makes it difficult to maintain the target temperature at low temperatures. Large temperature differences before and after the pipeline also affect its lifespan.
[0011] Therefore, to address the above problems, this invention first incorporates spiral fins on the inner tube. This forms a flow path for steam, allowing it to swirl and move across the inner tube surface, increasing its residence time in the heating space. Furthermore, it increases the heat transfer area, improving the heat transfer efficiency as the steam moves between the spiral fins. Common heating jackets are horizontally positioned, which results in hotter steam concentrating at the top of the jacket, effectively heating only one side of the slurry. Therefore, in practice, it is preferable to vertically position the heating jacket of this invention, with the steam inlet at the top and the steam outlet at the bottom. This ensures that the steam enters the jacket from the top and is evenly distributed across the heating space, effectively reducing localized insufficient heating caused by uneven steam distribution.
[0012] In enterprise production practices, a large amount of atmospheric pressure steam, known as esterification steam, is generated in processes such as polyester towers. This steam can be used as a source in the heating jacket of this invention. However, oligomers such as terephthalic acid in the esterification steam easily cool and condense inside the jacket as heat exchange occurs, especially on protruding structures such as the aforementioned spiral fins. This not only affects subsequent heating efficiency but also easily causes blockage. Therefore, this invention features a special design for the height of the spiral fins, ensuring they do not contact the outer tube, thus forming an annular flow channel through which steam can pass directly. This creates a combination of a swirling steam channel and an annular flow channel in the heating space, and the turbulence generated within the heating space can effectively flush away the condensed esterification impurities. Furthermore, by adjusting the height of the spiral fins, a suitable flow velocity is achieved on the outer surface of the inner tube, ensuring sufficient contact between the steam and the inner tube while preventing insufficient condensation of steam due to excessive flow velocity, thereby improving the utilization rate of steam thermal energy.
[0013] Preferably, the height of the spiral fins gradually increases from the steam inlet to the steam outlet. As the steam flows from top to bottom, its temperature gradually decreases. To compensate for this temperature loss, this invention features gradually increasing spiral fins on the inner tube, thereby increasing the heat exchange area and improving heating efficiency, resulting in more uniform heating by the heating jacket.
[0014] Preferably, the helix angle of the spiral fin is 25~30°.
[0015] Preferably, the steam inlet is connected to a steam trap. The steam trap is installed to promptly drain the water formed after steam condensation, preventing condensate buildup from affecting steam flow and heat transfer.
[0016] As a further preferred embodiment, the bottom of the heating space is provided with a collection tank for collecting impurities in the steam, and the bottom of the collection tank is connected to a cleaning port.
[0017] Preferably, the heating jacket also includes a pressure sensor disposed before the steam inlet and the steam trap.
[0018] Preferably, the outer surface of the outer pipe is covered with an insulation layer. This insulation layer reduces heat exchange between the steam inside the heating space and the outside of the pipe, thus improving steam utilization. In practice, a thick rock wool insulation layer with double-layer staggered joints is preferred.
[0019] As a further preferred embodiment, the end of the outer tube is provided with a flange for engaging the insulation layer.
[0020] As a further preferred embodiment, the insulation layer is covered with a protective layer. In practice, a thick galvanized iron sheet protective layer is preferred.
[0021] Preferably, the direction of slurry transport within the inner tube is opposite to the direction of steam transport. In practice, steam is transported from top to bottom, while the slurry flows from bottom to top, ensuring that the direction of slurry movement is opposite to the direction of steam temperature decrease, thus maximizing the temperature of the slurry at the outlet of the inner tube.
[0022] Therefore, this utility model has the following beneficial effects:
[0023] (1) By setting the steam inlet and outlet and the spiral fins, this utility model optimizes the steam delivery path, effectively increases the heat transfer area, and thus improves the utilization rate of steam, thereby achieving efficient and uniform heating of the slurry in the pipe.
[0024] (2) This utility model forms a combination of a steam swirling channel and an annular flow channel in the heating space, which makes targeted optimizations to the esterification steam and reduces the occurrence of impurity blockage in the heating space.
[0025] (3) This utility model achieves efficient energy saving and consumption reduction by optimizing the jacket structure, enhancing heat transfer and utilizing esterification steam. It not only reduces the production cost of enterprises, but also effectively responds to the national energy saving and consumption reduction policy, reduces energy consumption and greenhouse gas emissions, and has significant environmental benefits. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the structure of a heating jacket for a slurry pipeline in polyester production, according to Embodiment 1 of this utility model.
[0027] Figure 2 This is a cross-sectional view of a heating jacket for a slurry pipeline in polyester production, according to Embodiment 1 of this utility model.
[0028] Figure 3 This is a schematic diagram of the inner tube structure of a heating jacket for a slurry pipeline in polyester production, according to Embodiment 1 of this utility model.
[0029] Figure 4 This is a schematic diagram of the operation of a heating jacket for a slurry pipeline in polyester production, according to Embodiment 1 of this utility model.
[0030] Figure 5 This is a schematic diagram of the structure of a heating jacket for a slurry pipeline in polyester production, according to Embodiment 2 of this utility model.
[0031] Figure 6 This is a schematic diagram of the inner tube structure of a heating jacket for a slurry pipeline in polyester production, according to Embodiment 2 of this utility model.
[0032] In the diagram: 1. Process tower; 2. Air cooler; 3. Slurry tank; 4. First esterification reactor; 10. Inner tube; 11. Drain condenser; 12. Collection tank; 13. Cleaning port; 20. Outer tube; 21. Steam inlet; 22. Steam outlet; 23. Insulation layer; 24. Flange; 25. Protective layer; 30. Heating space; 31. Annular flow channel; 40. Spiral fins. Detailed Implementation
[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only a part of the embodiments of the present invention, and not all of the embodiments. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.
[0034] Example 1:
[0035] like Figure 1 As shown, a heating jacket for a slurry pipeline in polyester production according to this embodiment includes an inner pipe 10 and an outer pipe 20. The inner pipe 10 is DN200 (nominal diameter) and made of 316 stainless steel, used to transport slurry with a constant flow rate of approximately 25 t / h and a temperature of approximately 60°C. The outer pipe 20 is DN250 and made of Q235B carbon steel. A heating space 30 for accommodating steam is formed between the inner pipe 10 and the outer pipe 20. To reduce heat exchange between the steam and the outside air, the outer pipe 20 is covered with a 50 mm thick rock wool insulation layer 23, double-layered with staggered seams. The insulation layer 23 is covered with a 0.5 mm thick galvanized iron sheet as a protective layer 25. Both the inner pipe 10 and the outer pipe 20 are vertically arranged. The top of the outer pipe 20 is connected to a steam inlet 21, and a steam outlet 22 is provided on the bottom of the outer pipe 20 away from the steam inlet 21. The steam outlet 22 is also connected to a steam trap 11. Figure 3 As shown, to improve heat transfer efficiency, spiral fins 40 are provided on the outer surface of the inner tube 10. The spiral fins 40 are made of 316L stainless steel, with a mirror-polished surface, a thickness of 2mm, a spiral angle of 30°, a spiral fin height of 10mm, a pitch of 50mm, and the distance between the outer diameter of the thread and the inner diameter of the jacket outer tube is 5mm. A spiral fin 40 and the outer tube 20 form a... Figure 2The annular flow channel 31 is shown. In practice, the slurry flows from bottom to top through the inner tube 10. At this time, high-temperature esterification steam enters from the upper steam inlet 21. Part of the steam spirals down along the spiral fins 40. During this process, it transfers energy to the slurry in the inner tube 10 by contacting the large area of the spiral fins 40. The other part of the steam moves directly downward through the annular flow channel 31. The turbulence formed by the collision of the two parts of steam can clean the impurities remaining on the spiral fins 40 to a certain extent. After the steam reaches the bottom of the heating space 30, it is discharged through the steam outlet 22. At the same time, the water formed after the steam condenses is discharged in time through the steam trap 11 to prevent the accumulation of condensate from affecting the steam flow and heat transfer effect.
[0036] like Figure 4 As shown, to monitor and control the operation of the device, this embodiment includes temperature sensors installed at the inner tube slurry inlet (TI01), outlet (TI02), jacket steam inlet (TI03), and condensate outlet (TI04) to monitor the slurry and steam temperatures in real time. This embodiment also includes pressure sensors installed at the steam inlet (PI01) and before the steam trap (PI02) to monitor steam and condensate pressures. These sensors transmit data to the control system, which, based on preset temperature and pressure ranges, adjusts the regulating valve at the steam inlet to control the steam flow rate (FI01), ensuring the jacket heating system operates under optimal conditions. For example, when the slurry outlet temperature is detected to be lower than the set value, the control system automatically increases the opening of the steam regulating valve, increasing the steam flow rate and improving heating power; when the steam pressure is too high, the control system promptly adjusts the regulating valve to reduce the steam pressure, thereby ensuring the stable operation of the heating jacket.
[0037] Example 2:
[0038] like Figure 5 As shown, a heating jacket for a slurry pipeline in polyester production according to this embodiment includes an inner pipe 10 and an outer pipe 20, forming a heating space 30 for accommodating steam between the inner pipe 10 and the outer pipe 20. To reduce heat exchange between the steam and the outside air, the outer pipe 20 is covered with a thick layer of rock wool as an insulation layer 23, with double-layer staggered stitching, and the insulation layer 23 is covered with a thick galvanized iron sheet as a protective layer 25. At the end of the outer pipe 20, this embodiment also provides a flange 24 for engaging the insulation layer 23, thereby preventing the insulation layer 23 from sliding. Both the inner pipe 10 and the outer pipe 20 are vertically arranged. The top of the outer pipe 20 is connected to a steam inlet 21, and a steam outlet 22 is provided on the bottom of the outer pipe 20 away from the steam inlet 21. The steam outlet 22 is also connected to a steam trap 11. Figure 6As shown, to improve heat transfer efficiency, spiral fins 40 with gradually varying heights are provided on the outer surface of the inner tube 10. The spiral angle of the spiral fins 40 is 25°, thus forming an annular flow channel 31 that gradually decreases in size from top to bottom in the heating space 30. This gradually increases the heat transfer area and the steam flow rate. In practice, the slurry flows through the inner tube 10 from bottom to top. At this time, high-temperature esterification steam enters from the upper steam inlet 21. Part of the steam spirals down along the spiral fins 40, transferring energy to the slurry in the inner tube 10 through contact with the large area of the spiral fins 40. The other part of the steam moves directly downward through the annular flow channel 31. The turbulence formed by the collision of the two parts of steam can clean the impurities remaining on the spiral fins 40 to a certain extent. After the steam reaches the bottom of the heating space 30, it is discharged through the steam outlet 22. At the same time, the water formed by the condensation of the steam is discharged in time through the steam trap 11. During the operation of the device, impurities such as oligomers swept down by the turbulent flow fall into the collection tank 12 below, and after a period of time, the impurities can be cleaned out through the cleaning port 13.
[0039] The embodiments of this specification have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technological improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.
Claims
1. A heating jacket for slurry pipelines in polyester production, characterized in that: It includes an inner tube (10) for conveying slurry and an outer tube (20) sleeved outside the inner tube, such that a heating space (30) for containing steam is formed between the inner tube (10) and the outer tube (20). The outer tube (20) has a steam inlet (21) at one end and a steam outlet (22) at the other end, so that steam flows from the steam inlet (21) through the heating space (30) to the steam outlet (22). The inner tube (10) is provided with spiral fins (40) with the inner tube (10) as the axis. The height of the spiral fins (40) is less than the distance between the inner tube (10) and the outer tube (20), thereby forming an annular flow channel (31) that allows steam to pass directly through the heating space (30).
2. A heating jacket for slurry pipelines in polyester production according to claim 1, characterized in that: The height of the spiral fins (40) gradually increases from the steam inlet (21) to the steam outlet (22).
3. A heating jacket for slurry pipelines in polyester production according to claim 1, characterized in that: The helix angle of the spiral fin (40) is 25~30°.
4. A heating jacket for slurry pipelines in polyester production according to claim 1, characterized in that: The steam outlet (22) is connected to a steam trap (11).
5. A heating jacket for slurry pipelines in polyester production according to claim 4, characterized in that: The bottom of the heating space (30) is provided with a collection tank (12) for collecting impurities in the steam, and the bottom of the collection tank (12) is connected to a cleaning port (13).
6. A heating jacket for slurry pipelines in polyester production according to claim 5, characterized in that: It also includes pressure sensors installed at the steam inlet (21) and the steam trap (11), respectively.
7. A heating jacket for slurry pipelines in polyester production according to claim 1, characterized in that: The outer surface of the outer tube (20) is covered with a thermal insulation layer (23).
8. A heating jacket for slurry pipelines in polyester production according to claim 7, characterized in that: The outer tube (20) has a flange (24) at its end for engaging the insulation layer (23).
9. A heating jacket for slurry pipelines in polyester production according to claim 7, characterized in that: The insulation layer (23) is covered with a protective layer (25).
10. A heating jacket for slurry pipelines in polyester production according to claim 1, characterized in that: The direction of slurry transport in the inner tube (10) is opposite to the direction of steam transport.