A PCM-based prefabricated and assembled anti-freezing pipeline

Abstract

The present invention discloses a prefabricated and assembled anti-freezing pipeline based on PCM, which includes a medium transportation module, a heat preservation and anti-freezing module, and a breathing module; wherein, the medium transportation module is a working pipe for the distribution and storage of working medium and providing assembly reserved joints for different anti-freezing pipeline units; the heat preservation and anti-freezing module includes a PCM layer, a heat insulation layer, and a closed end; the fixing module includes an embedded bracket, a sleeve, and an O-shaped rubber seal ring; the breathing module is a breathing pipe; the working pipe 1 is located in the innermost layer; the PCM layer 2 is located in the cavity structure between the working pipe 1 and the sleeve 4; the embedded bracket 3 is fixed between the working pipe 1 and the sleeve 4; the heat insulation layer 5 is attached to the outside of the sleeve 4, and the sleeve 4 provides support and fixation for it. The present invention can solve technical problems such as prefabrication and assembly, module integration, no power facilities and energy consumption, simple structure, easy implementation, convenient operation and maintenance, economy and environmental protection of the anti-freezing pipeline.

Description

Technical Field

[0001] The present invention belongs to the technical field of pipeline anti-freezing, and specifically relates to a prefabricated anti-freezing pipeline based on PCM. Background Art

[0002] For a long time, in the northern regions, the anti-freezing technology of pipelines has always been the focus of attention of all parties. At present, the construction processes of common pipeline anti-freezing technologies all adopt non-prefabricated forms, and the technical measures are heat tracing and constant flow of the medium. Common heat tracing forms include electric heat tracing, steam heat tracing, and hot water heat tracing, etc. However, in engineering applications, both non-prefabricated forms and the above anti-freezing technologies have many defects.

[0003] From the perspective of construction process: First of all, for non-prefabricated forms, they are greatly affected by the quality of on-site personnel, with large construction and installation manual errors, and uneven product quality; secondly, compared with prefabricated and assembled forms, the on-site processing and installation construction period of non-prefabricated forms is long, and the time cost is relatively large; furthermore, non-prefabricated forms require a large number of on-site construction personnel, and due to the long construction period, the labor cost is high; finally, the anti-freezing products in non-prefabricated forms do not form a whole, resulting in serious waste of on-site materials and a large amount of industrial waste, and poor economic and environmental protection.

[0004] From the perspective of technical measures: First of all, heat tracing technology requires adding a heat tracing system and providing a heat source, and the steam and hot water heat tracing systems are particularly complex in design, construction, and construction, and the construction cost is very high; secondly, no matter which form, the current anti-freezing technology is accompanied by a large amount of energy or resource consumption, which runs counter to the current requirements of energy conservation and consumption reduction; finally, the current heat tracing systems all need to be maintained, and in order to prevent freezing in extreme weather, the heat tracing systems all adopt an over-matching strategy, resulting in huge maintenance costs and energy costs. Therefore, it is extremely urgent to research a prefabricated and assembled, modular integrated, low-energy consumption, simple structure, easy to implement, safe and efficient anti-freezing pipeline. Summary of the Invention

[0005] The purpose of the present invention is to provide a prefabricated anti-freezing pipeline based on PCM to solve technical problems such as prefabrication and assembly, modular integration, no power facilities and energy consumption, simple structure, easy implementation, convenient operation and maintenance, economy and environmental protection of anti-freezing pipelines.

[0006] In order to achieve the above-mentioned invention purpose, the technical solutions adopted by the present invention are as follows:

[0007] A PCM-based prefabricated anti-freezing pipeline, comprising a medium conveying module, a heat preservation and anti-freezing module, and a breathing module; wherein, the medium conveying module is a working pipe for the distribution and storage of working media and providing assembly reserved joints for different anti-freezing pipeline units; the heat preservation and anti-freezing module includes a PCM layer, a heat insulation layer, and a closed end; the fixing module includes an embedded bracket, a sleeve, and an O-ring; the breathing module is a breathing pipe; the working pipe 1 is located in the innermost layer; the PCM layer 2 is located in the cavity structure between the working pipe 1 and the sleeve 4; the embedded bracket 3 is fixed between the working pipe 1 and the sleeve 4; the heat insulation layer 5 is attached to the outer side of the sleeve 4, and the sleeve 4 provides support and fixation for it; the breathing pipe 6 is reserved and penetrates through the sleeve 4 and the heat insulation layer 5; the closed end 7 is fixed to the outer side of the PCM layer between different anti-freezing pipeline units; the PCM layer 2 for accommodating PCM materials, providing a place for the flow and solid-liquid phase change of PCM, and providing phase change latent heat for the anti-freezing of the pipeline for energy protection is not filled with PCM materials during use, providing a buffer space for the volume change of the PCM materials during solid-liquid phase change; the embedded bracket 3 for maintaining the cavity between the working pipe 1 and the sleeve 4 to provide fixation and support is a dendritic structure suitable for the mutual flow of liquid PCM on both sides, which is beneficial to PCM perfusion; the sleeve 4 and the working pipe 1 jointly provide an accommodating cavity for the PCM layer 2; the sleeve 4 provides support and fixation for the heat insulation layer 5, and at the same time the sleeve 4 provides a reserved installation position for the breathing pipe 6; the heat insulation layer 5 for reducing the heat release rate of the PCM layer 2 and maintaining the gradually slow and controllable release of the phase change latent heat of the PCM layer 2 provides a reserved installation position for the breathing pipe 6; one breathing pipe 6 is installed in each anti-freezing pipeline unit, and this breathing pipe penetrates through the sleeve 4 and the heat insulation layer 5, and the breathing pipe 6 provides a channel for the inhalation and exhalation of the air in the cavity of the PCM layer 2, maintaining the air pressure balance and air pressure isolation of the PCM layer 2, and reducing the volatilization of the medium; the closed end 7 seals and partitions the PCM materials in the PCM layer 2, forming independent pipeline anti-freezing units. The O-ring 10 seals the connection of the pipeline units of the working pipe 1, which is used to avoid the leakage of working media, and at the same time prevent the entry of external air into the working pipe 1, reducing the occurrence of corrosion inside the pipe.

[0008] A stop valve is installed on the breathing pipe. When the PCM material is poured into the cavity structure of the PCM layer 2, the breathing pipe 6 is opened to discharge the air in the cavity; when the pouring of the PCM material is completed, the breathing pipe 6 is closed to avoid the leakage of PCM materials, the volatilization of the medium, and the entry of air.

[0009] After the assembly reserved joints of the working pipe are connected, they are sealed with the O-ring 10 to avoid the leakage of working media, the entry of external air, and corrosion. The outer layer is a heat insulation layer made on-site.

[0010] The advantages and positive effects of the present invention are as follows:

[0011] 1. Closed ends and on-site insulation positions are reserved, and the technical effects are as follows:

[0012] (1) It is beneficial to on-site installation, with simple operation and strong flexibility. At the interface position of the pipeline connection unit of the present invention, closed ends and positions for making up insulation are reserved. Multiple connection methods such as crimping, welding, and threading can be adopted. At the construction site, only the reserved position needs to be found and simple operations can complete good insulation measures. Compared with the comparative invention, the first 4 items do not consider the pipeline connection position. Although the invention CN104913153A considers pipeline connection, it uses flange connection. Since the flange itself is relatively large, it is difficult to make up insulation on-site, and the flange at the connection also needs to be insulated separately. The installation difficulty and material loss of the comparative invention are both relatively large.

[0013] (2) It is beneficial to the local insulation and energy conservation at the pipeline unit connection position. The connection position of the pipeline unit is the place where the assembled pipeline is most likely to have energy loss. By reserving closed ends and insulation positions, the local heat loss at the connection can be greatly improved in actual projects, achieving the effect of energy conservation.

[0014] 2. The present invention has an O-shaped rubber sealing ring, and the technical effects are as follows:

[0015] (1) The fixed sealing effect is good. It can prevent the leakage of the medium in the working pipe and the entry of outdoor gas, ensuring safety and reducing the occurrence of the phenomenon of air corroding the working pipe;

[0016] (2) It can perform dynamic sealing. During the assembly construction process, it can be used as a dynamic sealing element for axial reciprocating motion and low-speed rotational motion, and can adapt to installation situations such as pipeline rotation.

[0017] (3) It is beneficial to making up insulation on-site and improving the anti-freezing effect at the connection position. It increases the friction between the working pipe and the on-site made-up insulation, facilitating the installation of the made-up insulation and enhancing the anti-freezing effect at the pipeline unit connection position.

[0018] 3. The thickness of the PCM layer is the same as that of the insulating layer:

[0019] Through a large amount of calculations and data analysis, it is found that when the thickness of the PCM layer is the same as that of the insulating layer, the anti-freezing time is the longest and the anti-freezing effect is the best.

[0020] 4. The present invention is provided with an embedded bracket;

[0021] (1) It is beneficial to the flow and heat storage of PCM. Due to the inclusion of an embedded bracket, the liquid PCM can flow freely in the cavity space, greatly facilitating the flow and heat storage of the phase change material during the heat storage stage, being beneficial to enhancing heat transfer and increasing the heat storage capacity.

[0022] (2) It is beneficial to support and force balance, reducing deformation. Under the action of the embedded bracket, the anti-freezing structure is in force balance and not prone to deformation;

[0023] (3) It is beneficial to extend the service life of the anti-freezing structure. The embedded bracket can enhance the stability of the anti-freezing structure, reduce the possibility of deformation of the outermost insulation layer of the PCM layer, and also help to enhance the durability and service life of the anti-freezing structure.

[0024] (4) When the phase change volume of the PCM material changes, it can provide a certain volume change space for the PCM.

[0025] (5) It is beneficial to improve the product precision and quality. Due to the inclusion of the embedded bracket, the embedded bracket with appropriate dimensions can be designed and processed according to factors such as the environment, the size of the working pipe, and the medium temperature, thereby controlling the precision of the anti-freezing product.

[0026] 5. The casing and insulation layer materials of the present invention are variable, and it has good environmental adaptability;

[0027] For example, if the pipeline is laid overhead, the present invention can select casings and insulation layers made of materials with relatively low density and low thermal conductivity, which is not only beneficial to extending the anti-freezing time, but also can reduce the weight of the pipeline system, reduce the number of support components, improve the environmental adaptability, and also reduce the investment.

[0028] Another example: When laying anti-freezing pipelines on the seabed, corrosion-resistant casings and insulation layers can be selected according to the seawater corrosion, greatly improving the environmental adaptability and durability.

[0029] 6. Improve the project quality. By using factory prefabricated components, processing and assembling the components, modularization and integration are achieved, reducing the installation errors caused by uneven qualities of on-site construction workers, reducing the occurrence of quality accidents, improving the product reliability, and ensuring the project quality.

[0030] 7. Improve the time utilization rate and production efficiency. Batch processing and production of anti-freezing devices in a prefabrication factory reduce the unnecessary number of pipe segments; the assembled installation has simple and clear connection interfaces, saving the on-site construction time and greatly improving the time utilization rate and production efficiency;

[0031] 8. High standardization degree. The component structure is simple, and the shape and size are easy to standardize, facilitating prefabrication, transportation, and assembly, with a high assembly rate and standardization degree.

[0032] 9. Energy conservation and environmental protection. Combining the high phase change latent heat characteristics of PCM and the low thermal conductivity characteristics of the solid phase of PCM, the tracing system and heat source are eliminated, and the freezing risk in extreme weather can be effectively reduced without additional energy, truly achieving passive and zero energy consumption during operation, energy conservation and environmental protection.

[0033] 10. Convenient operation and maintenance. Since the solid-liquid two-phase of the PCM can be frequently transformed, after the system is installed once, it can be reused without special care, and the operation and maintenance are simple.

[0034] 11. Wide application range. This method can be applied to various environments, such as air, soil, oil, water, space, etc. It can be widely applied to systems such as fire protection, water supply, rainwater, sewage, air-conditioning water, etc. As long as the PCM meeting the requirements is selected according to the application environment and working requirements.

[0035] 12. Great economic advantages. On the one hand, by adopting the prefabricated and assembled method, the material waste in the construction and operation stages is greatly reduced, and the labor and operation and maintenance costs are reduced. On the other hand, due to the advantages of the phase change anti-freezing technology, taking the buried pipe as an example, in the cold regions in the north or west, the anti-freezing layer is about 2.5m - 3m. By using this method, the pipe burial depth can be effectively reduced, thus greatly reducing the pipe laying investment and maintenance cost; taking the overhead pipe as an example, this method has no tracing heat and circulation energy consumption, and the advantages are obvious. Description of the Drawings

[0036] Figure 1 is the schematic diagram of the overall structure of the present invention;

[0037] Figure 2 is the axial sectional view of the anti-freezing pipe of the present invention;

[0038] Figure 3 is the radial 1-1 sectional view of the anti-freezing pipe of the present invention;

[0039] Figure 4 is the radial 2-2 sectional view of the anti-freezing pipe of the present invention;

[0040] Figure 5 is the partial enlarged view of the connection part of the anti-freezing pipe of the present invention.

[0041] Figure 6 is the partial sectional enlarged view of the breather pipe of the present invention.

[0042] Reference numerals in the drawings: 1 - working pipe, 2 - PCM layer, 3 - embedded bracket, 4 - sleeve, 5 - heat insulation layer, 6 - breather pipe, 7 - closed end, 8 - on-site supplementary heat preservation, 9 - pipeline unit connection interface, 10 - O-ring seal. Detailed Embodiment

[0043] A prefabricated and assembled anti-freezing pipe based on PCM mainly includes a medium transportation module, a heat preservation and anti-freezing module, and a breathing module. Among them, the medium transportation module: working pipe; the heat preservation and anti-freezing module: PCM layer, heat insulation layer, closed end; the fixing module: embedded bracket, sleeve, O-ring seal; the breathing module: breather pipe.

[0044] For the specific structure of the present invention, refer to Figure 1 : The figure shows a schematic structural diagram of three pipeline units. The working pipe 1 is located in the innermost side; the PCM layer 2 is located in the cavity structure between the working pipe 1 and the casing 4; the embedded bracket 3 is fixed between the working pipe 1 and the casing 4; the heat insulation layer 5 is attached to the outer side of the casing 4, and the casing 4 provides support and fixation for it; refer to Figure 2 , 3 as shown Figure 3 is a schematic radial cross-sectional view, showing the position structure of the embedded bracket. The breathing pipe 6 is reserved and penetrates through the casing 4 and the heat insulation layer 5; the closed end 7 is fixed to the outer side of the PCM layer between different anti-freezing pipeline units; the O-ring rubber seal 10 is fixed at the connection of the anti-freezing pipeline unit, and the outer layer thereof is the on-site supplementary insulation 8.

[0045] The working pipe 1 is used for the transportation and storage of working media, and provides assembly reserved joints for different anti-freezing pipeline units, facilitating installation and on-site supplementary insulation during on-site assembly.

[0046] The PCM layer 2 is used to accommodate PCM materials, provide a place for the flow and solid-liquid phase change of PCM, and provide phase change latent heat for the anti-freezing of the pipeline for energy protection. At the same time, the PCM layer 2 is not filled with PCM materials during use, providing a buffer space for the volume change of the PCM materials during solid-liquid phase change.

[0047] The embedded bracket 3 provides fixation and support for maintaining the cavity between the working pipe 1 and the casing 4. At the same time, since the embedded bracket 3 is a branched structure, it is convenient for the liquid PCM on both sides of the embedded bracket 3 to flow to each other, which is beneficial to PCM perfusion.

[0048] The casing 4 and the working pipe 1 jointly provide an accommodation cavity for the PCM layer 2. The casing 4 provides support and fixation for the heat insulation layer 5. At the same time, the casing 4 provides a reserved installation position for the breathing pipe 6.

[0049] The heat insulation layer 5 is used to reduce the heat release rate of the PCM layer 2 and maintain the gradual and controllable release of the phase change latent heat of the PCM layer 2. The heat insulation layer 5 provides a reserved installation position for the breathing pipe 6.

[0050] Refer to Figure 4 as shown, which is a radial cross-sectional view of the anti-freezing pipeline, showing the position structure of the breathing pipe. Refer to Figure 6Partial enlarged sectional view of the breather tube. The breather tube 6 passes through the sleeve 4 and the heat insulation layer 5, and one is installed for each anti-freezing pipeline unit. Since the PCM material in the PCM layer 2 is not completely filled, there is a volume change when the PCM material expands and contracts due to heat, and the breather tube 6 provides a channel for the inhalation and exhalation of the air in the cavity of the PCM layer 2, maintains the air pressure balance and air pressure isolation of the PCM layer 2, reduces the volatilization of the medium, and provides safety protection for the PCM layer 2. In addition, when the PCM material is injected into the cavity structure of the PCM layer 2, the breather tube 6 is opened to discharge the air in the cavity; when the injection of the PCM material is completed, the breather tube 6 is closed to prevent the leakage of the PCM material, the volatilization of the medium and the entry of air, and improve the anti-freezing effect of the PCM layer 2.

[0051] The closed end 7 seals and partitions the PCM material in the PCM layer 2 to form an independent pipeline anti-freezing unit, which is convenient for storing the PCM material.

[0052] See Figure 5 As shown, it is a partial enlarged view of the connection of the anti-freezing pipeline of the present invention, reflecting the positional relationship of the connection of the pipeline unit, the closed end, the O-ring rubber seal and the on-site heat insulation supplement.

[0053] The specific implementation process of the prefabrication and assembly of the present invention is as follows: First, the main components such as the working pipe, the embedded bracket, the sleeve, the heat insulation layer, the breather tube, the closed end, the O-ring rubber seal of the present invention are prefabricated and processed in the factory; then, according to the process requirements and the on-site conditions, select the appropriate PCM material, complete the pouring and encapsulation of the PCM layer, and determine the connection form and connection pipe fittings at the same time; then, assemble according to the module functions and positions in the factory to form an integrated anti-freezing pipeline unit; finally, transport the assembled anti-freezing pipeline unit to the construction site, splice and install according to the reserved interface position, fix the O-ring rubber seal, and supplement the heat insulation on-site at the connection of the pipeline unit.

[0054] The PCM mentioned in the present invention, that is, the phase change material, refers to a class of materials that can absorb or release a large amount of energy (i.e., the phase change enthalpy) when the substance undergoes a phase change. The phase change material uses latent heat for heat storage and heat release, has the characteristics of large heat storage density, compact structure of the heat storage device, basically unchanged temperature of itself during the phase change process, and easy management, etc., and has great potential for engineering applications.

[0055] The core of adopting the PCM technology lies in filling a phase change medium that is liquid at normal temperature into the PCM layer 2, and the solid-liquid phase change temperature of this medium is close to and higher than the anti-freezing temperature (non-freezing temperature) of the working medium. In practical applications, different PCM materials are selected according to different working media and anti-freezing times. When the ambient temperature is higher than the solidification point of the PCM, it is in a non-anti-freezing state. At this time, the PCM is in a liquid state and in a heat storage state, jointly playing a heat preservation and heat insulation role with the heat insulation layer 5. When the ambient temperature is lower than the solidification point of the PCM, it enters the anti-freezing state. The PCM in the pipeline phase change module 2 starts to release latent heat and gradually changes from a liquid state to a solid state. This heat release process has the following characteristics:

[0056] A. The heat release rate is slow and the phase change heat release time is long. Due to the protection of the heat insulation layer 5, the heat release rate of the pipeline phase change module 2 is slow. In general designs, after setting the heat insulation layer, the heat release rate of the pipeline is about 50 W / (㎡·℃). In comparison, the latent heat of PCM phase change is huge. Therefore, the PCM in the PCM layer 2 needs a relatively long time to complete the phase change process.

[0057] B. The PCM layer 2 has temperature stability during the phase change process. Due to the characteristic B, the pipeline is in a solid-liquid conversion process for a long time, and the substance is approximately at a constant temperature during the phase change process. Therefore, the PCM layer 2 will remain at the solidification point temperature for a relatively long period of time. This characteristic is beneficial to the stable operation of the working pipe 1.

[0058] C. Due to the existence of the PCM layer 2, there is a heat release vacuum period for the working pipe 1. The characteristic of this property is that if the temperature of the medium in the working pipe 1 is higher than the temperature of the pipeline phase change module, the heat will continuously enter the heat insulation layer through the pipeline phase change module, thereby prolonging the solidification time of the pipeline phase change module; after the temperature of the working medium is the same as the temperature of the pipeline phase change module, it will no longer decrease because there is no driving force for heat transfer when the two temperatures are the same. Therefore, during the liquid-solid conversion period of the pipeline phase change module, the working medium will be in a heat release vacuum state for a long time and will not release heat to the outside. This state is of great significance for the anti-freezing of the pipeline.

[0059] D. After the PCM material in the PCM layer 2 is completely transformed into a solid phase, it evolves into a heat-insulating material. Since the thermal conductivity of the selected PCM material in the solid phase is lower than that of conventional heat-insulating materials, after the PCM material is completely transformed into a solid phase, the PCM layer 2 is completely evolved into a heat-insulating layer. The significance of this feature is that since the freezing point of the PCM is adjacent to and higher than the anti-freezing temperature of the pipeline medium of the working pipe 1 and much higher than the freezing temperature of the pipeline medium of the working pipe 1. In the event of extreme weather, even if the entire PCM layer 2 is transformed into a solid state, it can still serve as a good heat-insulating material and, together with the heat-insulating layer 5, form a new superimposed heat-insulating layer, reducing the heat release rate and slowing down the transition of the medium in the working pipe 1 from the anti-freezing temperature to the freezing temperature, thereby effectively extending the freezing time of the medium in the pipeline of the working pipe 1.

Claims

1. A prefabricated and assembled anti-freezing pipeline based on PCM, characterized in that, It includes a medium transportation module, a heat preservation and anti-freezing module, and a breathing module; among them, the medium transportation module is a working pipe used for the distribution and storage of the working medium and providing assembly reserved joints for different anti-freezing pipe units; the heat preservation and anti-freezing module includes a PCM layer, a heat insulation layer, and a closed end; the fixing module includes an embedded bracket, a sleeve, and an O-ring rubber seal; the breathing module is a breathing pipe; the working pipe is located in the innermost layer; the PCM layer is located in the cavity structure between the working pipe and the sleeve; the embedded bracket is fixed between the working pipe and the sleeve; the heat insulation layer is attached to the outer side of the sleeve, and the sleeve provides support and fixation for it; the breathing pipe is reserved and penetrates through the sleeve and the heat insulation layer; the closed end is fixed to the outer side of the PCM layer between different anti-freezing pipe units; the O-ring rubber seal for sealing the connection of the pipe units of the working pipe is fixed to the connection of the pipe units of the working pipe; the PCM layer for accommodating the PCM material, providing a place for the flow and solid-liquid phase change of the PCM, and providing latent heat of phase change for the anti-freezing of the pipe for energy protection is not filled with PCM material during use, providing a buffer space for the volume change of the PCM material during solid-liquid phase change; the embedded bracket for maintaining the cavity between the working pipe and the sleeve to provide fixation and support is a dendritic structure suitable for the mutual flow of liquid PCM on both sides and conducive to PCM perfusion; the sleeve and the working pipe jointly provide an accommodating cavity for the PCM layer; the sleeve provides support and fixation for the heat insulation layer, and at the same time the sleeve provides a reserved installation position for the breathing pipe; the PCM layer and the heat insulation layer have the same thickness; the heat insulation layer for reducing the heat release rate of the PCM layer and maintaining the gradual, slow, and controllable release of the latent heat of phase change of the PCM layer provides a reserved installation position for the breathing pipe; one breathing pipe is installed for each anti-freezing pipe unit, and this breathing pipe penetrates through the sleeve and the heat insulation layer. The breathing pipe provides a channel for the inhalation and exhalation of the air in the cavity of the PCM layer, maintains the air pressure balance and air pressure isolation of the PCM layer, and reduces the volatilization of the medium; the closed end seals and partitions the PCM material in the PCM layer to form an independent pipe anti-freezing unit.

2. The prefabricated and assembled anti-freezing pipeline based on PCM according to claim 1, characterized in that, A stop valve is installed on the breathing pipe. When the PCM material is injected into the cavity structure of the PCM layer, the breathing pipe opens to discharge the air in the cavity; when the PCM material injection is completed, the breathing pipe is closed to avoid the leakage of the PCM material, the volatilization of the medium, and the entry of air.

3. The prefabricated and assembled anti-freezing pipeline based on PCM according to claim 1, wherein, After the assembly reserved joints of the working pipe are connected, they are sealed with the O-ring rubber seal, and the outer layer is a heat insulation layer made on-site.

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