A measurement tube insulation bridge structure

Abstract

The utility model provides a kind of measurement pipe heat insulation bridge structure, belong to measurement pipe heat insulation technical field, this measurement pipe heat insulation bridge structure is used to connect the inside portion and outside portion of measurement pipe, including annular support seat, bridging arm, heat conduction blocking layer and fixed ring;The annular support seat is set on the inner wall of measurement pipe, the first end of bridging arm with the outer surface of annular support seat is connected, the second end of bridging arm extends to the outer wall position of measurement pipe, the heat conduction blocking layer is covered in the outer surface of bridging arm, the fixed ring is set in the second end outside of bridging arm, the fixed ring and the outer wall of measurement pipe interference fit, it is characterized in that, bridging arm is wavy structure on axial section, the wavy structure has at least three wave crest and two wave troughs alternate arrangement, the heat conduction blocking layer is closely attached the wavy outer surface of bridging arm.

Description

Technical Field

[0001] This utility model belongs to the field of measuring tube insulation technology, specifically, it relates to a measuring tube insulation bridge structure. Background Technology

[0002] In industries such as petrochemicals, energy and power, and metallurgical manufacturing, temperature measurement is a critical aspect of process control. Measuring tubes, serving as the mounting carrier and protective device for temperature sensors, need to be inserted into high- or low-temperature process media for real-time temperature monitoring. In practical applications, the temperature of the process media inside the measuring tube often reaches hundreds of degrees Celsius or even higher, while the outside of the measuring tube is exposed to a relatively low-temperature environment. This significant temperature difference makes the measuring tube wall the primary channel for heat transfer. In traditional measuring tube designs, the measuring tube wall typically uses a single-layer metal structure, allowing heat to be transferred directly from the inside to the outside through the metal wall. This causes a rapid rise in the temperature of the outer wall of the measuring tube, resulting not only in energy loss but also posing a threat to the safety of surrounding equipment and personnel. To reduce this heat transfer, existing technologies mainly employ two solutions. One is to add a heat-insulating sleeve to the outside of the measuring tube and fill the space between the measuring tube and the sleeve with heat-insulating material. However, this solution increases the overall structural size, limits installation space, and the filling material is prone to aging and failure under long-term high-temperature environments. The other solution is to use a double-layer measuring tube structure, creating a vacuum or filling it with inert gas between the inner and outer tubes. However, this solution has high manufacturing costs, strict sealing requirements, and is difficult to maintain. Once the seal fails, the heat insulation performance drops sharply. In addition, existing heat insulation structures often neglect the impact of thermal stress on the lifespan of the measuring tube. During frequent heating and cooling cycles, the thermal stress concentration caused by the temperature difference between the inside and outside of the measuring tube can generate fatigue cracks at the connection points, eventually leading to the failure of the measuring tube. This not only increases maintenance costs but may also cause production interruptions and safety accidents. Therefore, there is an urgent need for a heat insulation structure for measuring tubes that can effectively insulate and disperse thermal stress, has a compact structure, and is easy to install and maintain. Utility Model Content

[0003] In view of this, the present invention provides a thermal bridge structure for a measuring tube, which can solve the problem in the prior art where, during temperature measurement, the high-temperature or low-temperature medium inside the measuring tube exchanges heat directly with the external environment through the tube wall, resulting in a large temperature gradient between the inside and outside of the measuring tube. This temperature gradient causes significant thermal stress on the tube wall, which can lead to deformation, cracks, or even breakage and failure of the measuring tube over long-term use. At the same time, the rapid heat transfer also affects the measurement accuracy of the temperature sensor, causing significant deviations in the measurement data. Especially in industrial processes requiring precise temperature control, this problem of rapid heat transfer and thermal stress concentration seriously affects the reliability and accuracy of the measurement system. Existing insulation solutions usually use simple sleeve structures or fill with insulation materials, but these solutions either have limited insulation effects or are complex in structure and difficult to install and maintain, failing to simultaneously meet the requirements of efficient insulation, compact structure, and long-term reliable use.

[0004] This utility model is implemented as follows:

[0005] This utility model provides a thermal bridge structure for a measuring tube, used to connect the inner and outer parts of a measuring tube. It includes an annular support, a bridging arm, a thermally insulating layer, and a fixing ring. The annular support is disposed on the inner wall of the measuring tube. The first end of the bridging arm is connected to the outer circumferential surface of the annular support, and the second end of the bridging arm extends to the outer wall of the measuring tube. The thermally insulating layer covers the outer surface of the bridging arm. The fixing ring is sleeved on the outer side of the second end of the bridging arm and is interference-fitted with the outer wall of the measuring tube. The bridging arm has a wavy structure in its axial cross-section, with at least three peaks and two troughs arranged alternately. The thermally insulating layer is tightly fitted to the wavy outer surface of the bridging arm.

[0006] The technical advantages of the measuring tube thermal bridge structure provided by this utility model are as follows: By designing the bridging arm as a wave-shaped structure and covering it with a thermally conductive blocking layer, the path length for heat to be transferred from the inside to the outside of the measuring tube is significantly extended. The multiple peaks and troughs of the wave-shaped structure require the heat flow to take more tortuous paths to pass through the bridging arm. At the same time, the thermally conductive blocking layer is tightly attached to the wave-shaped outer surface to further block heat conduction. The interference fit between the fixing ring and the outer wall of the measuring tube ensures the stability and sealing of the overall structure, effectively reducing the heat exchange rate between the inside and outside of the measuring tube, and improving the accuracy and stability of temperature measurement. It is particularly suitable for industrial measurement scenarios that require precise temperature control.

[0007] Based on the above technical solution, the measuring tube heat insulation bridge structure of this utility model can be further improved as follows:

[0008] The annular support base has multiple radial reinforcing ribs on its inner circumferential surface. The radial reinforcing ribs are evenly distributed along the circumference of the annular support base, and the radial height of the radial reinforcing ribs decreases from the inner circumferential surface of the annular support base towards the geometric center.

[0009] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting multiple radial stiffeners on the inner circumferential surface of the annular support and distributing them evenly along the circumference, the radial stiffness and deformation resistance of the annular support are significantly enhanced. The design of the radial stiffener height decreasing from the inner circumference to the geometric center makes the stress distribution more uniform, avoiding structural failure caused by local stress concentration. At the same time, the evenly distributed stiffeners ensure the stress balance at the connection point of the bridging arm, preventing loosening or breakage of the connection due to excessive local load, and further improving the reliability and service life of the entire thermal insulation bridge structure during long-term use.

[0010] Furthermore, the radius of curvature at the crest of the bridging arm is smaller than the radius of curvature at the trough of the bridging arm, and the transition section between the crest and the trough is a smooth curved surface connection.

[0011] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by making the radius of curvature at the top of the bridging arm crest smaller than the radius of curvature at the bottom of the trough, a more abrupt bend is formed at the crest position, further increasing the tortuosity of the heat flow transfer path. The smooth curved surface transition between the crest and the trough avoids the generation of stress concentration points, preventing the initiation and propagation of cracks caused by thermal stress during temperature cycling. This differentiated curvature design not only ensures the mechanical strength of the structure, but also maximizes the extension of the heat conduction path. At the same time, the smooth transition section reduces the interface stress between the heat conduction blocking layer and the bridging arm, improving the bonding strength between the two.

[0012] Furthermore, the inner circumferential surface of the fixing ring is provided with a spiral groove, the helix angle of the spiral groove is the ratio of the axial length of the fixing ring to its circumference, and the bottom of the spiral groove forms a clearance fit with the outer surface of the second end of the bridging arm.

[0013] The beneficial effects of adopting the above-mentioned improved scheme are as follows: By setting a spiral groove structure on the inner circumference of the fixed ring, the spiral groove guides the fixed ring to gradually fit onto the outer side of the second end of the bridging arm along the spiral trajectory during the assembly process. The specific design of the spiral helix angle makes the assembly force reasonably distributed, reducing the risk of extrusion damage to the heat-conducting barrier layer during the assembly process. The clearance fit between the bottom of the spiral groove and the outer surface of the second end of the bridging arm not only ensures the smoothness of the assembly, but also achieves reliable fixation of the bridging arm through elastic deformation after the interference fit between the fixed ring and the outer wall of the measuring tube. At the same time, the spiral groove structure also plays a stress buffering role, reducing connection failure caused by thermal expansion and contraction.

[0014] Furthermore, the thermally conductive blocking layer has a multi-layered concentric ring structure in cross-section. The multi-layered concentric ring structure consists of a first blocking layer, a second blocking layer, and a third blocking layer from the inside out, and the layers are connected by an adhesive bonding method.

[0015] The beneficial effects of adopting the above-mentioned improved scheme are as follows: by designing the thermally conductive blocking layer into a multi-layered concentric ring structure and sequentially setting the first blocking layer, the second blocking layer, and the third blocking layer from the inside out, multiple thermal resistance barriers are formed. The interface formed by the adhesive connection between each blocking layer further increases the thermal conduction resistance. The multi-layered structure requires heat to cross different material interfaces multiple times during the transfer process, and each crossing will generate an increase in thermal resistance. This layered design has better thermal insulation performance than a single-layer structure. At the same time, the adhesive connection between each layer ensures the integrity of the overall structure and avoids the decrease in thermal insulation performance caused by interlayer peeling.

[0016] Furthermore, the outer circumferential surface of the annular support is provided with an annular boss, the end face of the first end of the bridging arm abuts against the side of the annular boss, and the first end of the bridging arm is fixed to the side of the annular boss by welding.

[0017] The beneficial effects of adopting the above-mentioned improved scheme are as follows: by setting an annular boss on the outer circumference of the annular support and making the end face of the first end of the bridging arm abut against the side of the annular boss, the contact area between the bridging arm and the annular support is increased, making the stress distribution at the connection more uniform. The design of fixing the bridging arm to the side of the annular boss by welding ensures the high strength and airtightness of the connection. The welded connection can withstand large mechanical loads and thermal stresses. The structure of the annular boss also plays a positioning role, which makes it easy to quickly and accurately determine the installation position of the bridging arm during the assembly process, improving assembly efficiency and assembly quality. At the same time, the welded connection eliminates the loosening risk that may be caused by bolted connections.

[0018] Furthermore, the wavy structure of the bridging arm has three wave crests, the axial spacing between two adjacent wave crests is equal, and the depth of the wave trough is 1 / 5 to 1 / 4 of the total axial length of the bridging arm.

[0019] The beneficial effects of adopting the above-mentioned improved scheme are as follows: by limiting the number of wave crests of the bridging arm wave structure to three and making the axial spacing between adjacent wave crests equal, sufficient insulation path length is ensured while avoiding structural complexity and increased processing difficulty caused by too many wave crests. The depth of the wave trough is controlled within the range of 1 / 5 to 1 / 4 of the total axial length of the bridging arm, which ensures the insulation effect of the wave structure and avoids insufficient local strength of the bridging arm due to excessively deep wave troughs. The equally spaced wave crest design makes the stiffness distribution of the entire bridging arm uniform and prevents stress concentration caused by abrupt changes in stiffness. This parameter optimization design achieves the best balance between thermal insulation performance and mechanical performance.

[0020] Furthermore, the outer circumferential surface of the fixing ring is provided with a plurality of axially distributed positioning grooves, the groove openings of the positioning grooves facing the radially outer side of the fixing ring, and the groove depth of the positioning grooves being 1 / 3 to 1 / 2 of the wall thickness of the fixing ring.

[0021] The beneficial effects of adopting the above-mentioned improved scheme are as follows: By setting multiple axially distributed positioning grooves on the outer circumference of the fixed ring and making the groove openings face radially outward, a reliable positioning reference and fixed position are provided for the installation and fixing components on the outside of the measuring tube. The groove depth is controlled at 1 / 3 to 1 / 2 of the wall thickness of the fixed ring, which ensures that the positioning groove has sufficient accommodating depth and avoids weakening the overall strength of the fixed ring due to excessive groove depth. The multiple axially distributed positioning grooves make the fixing force evenly distributed along the axial direction, preventing the fixed ring from deforming or being damaged due to excessive local fixing force. At the same time, the positioning grooves also play an anti-rotation role, ensuring that the installation orientation of the heat insulation bridge structure on the measuring tube remains stable.

[0022] Furthermore, the bridging arm is made of stainless steel, the thermally insulating layer is made of polytetrafluoroethylene, and the annular support and the fixing ring are both made of aluminum alloy.

[0023] The beneficial effects of adopting the above-mentioned improved scheme are as follows: by selecting stainless steel to manufacture the bridging arm, the good mechanical strength, corrosion resistance and processing performance of stainless steel are fully utilized, and it can withstand the mechanical stress and chemical corrosion in the environment in which the measuring tube is used. The thermal insulation layer is made of polytetrafluoroethylene, which utilizes its extremely low thermal conductivity and excellent high and low temperature resistance to achieve efficient heat insulation. The annular support and fixing ring are made of aluminum alloy, which not only ensures sufficient mechanical strength, but also reduces the weight of the overall structure. This material combination scheme gives full play to the performance advantages of various materials and achieves comprehensive optimization of structural strength, heat insulation performance and lightweight.

[0024] Furthermore, the end face of the second end of the bridging arm is provided with an annular groove, and the inner circumferential surface of the fixing ring is provided with an annular protrusion that mates with the annular groove at a corresponding position. The annular protrusion is embedded in the annular groove to form an axial limiting fit.

[0025] The beneficial effects of the above-mentioned improvement scheme are as follows: By setting an annular groove on the end face of the second end of the bridging arm and setting a corresponding annular protrusion on the inner circumference of the fixing ring, a reliable axial limiting mechanism is formed. The fit of the annular protrusion embedded in the annular groove prevents the bridging arm from moving relative to the ground under axial force. In particular, it can effectively maintain the relative position stability between the bridging arm and the fixing ring when the measuring tube is subjected to vibration or impact load. This axial limiting fit and the interference fit of the fixing ring work together to form a double constraint in the axial and radial directions, which significantly improves the vibration resistance and positional stability of the entire thermal insulation bridge structure and ensures the reliability of measurement accuracy during long-term use.

[0026] Compared with existing technologies, the beneficial effects of the measuring tube thermal bridge structure provided by this utility model are as follows: This utility model fundamentally solves the technical problems of rapid heat transfer and thermal stress concentration inside and outside the measuring tube by innovatively designing the bridging arm into a wave-shaped structure and combining it with multiple thermally conductive blocking layers. The wave-shaped bridging arm makes the heat flow path present a three-dimensional tortuous state. Compared with the traditional straight bridging structure, the heat flow path length is increased several times. Combined with the tightly fitted multiple thermally conductive blocking layers, multiple thermal resistance barriers are set up on the heat flow path. The interface between each blocking layer will generate a significant increase in thermal resistance, which greatly improves the overall thermal resistance value. The radial reinforcing ribs on the annular support and the spiral groove structure of the fixing ring work together to ensure the mechanical strength and assembly reliability of the structure, and avoid local stress concentration through reasonable stress dispersion design. In terms of material selection, a combination of stainless steel, polytetrafluoroethylene and aluminum alloy is used to give full play to the performance advantages of each material and achieve an organic unity of high strength, high thermal insulation and lightweight. The annular groove at the second end of the bridging arm engages axially with the annular protrusion of the fixing ring, and together with the interference fit between the fixing ring and the outer wall of the measuring tube, a dual constraint mechanism of axial and radial constraints is formed, ensuring the long-term stability of the structure under vibration and thermal cycling conditions. The entire structural design cleverly integrates thermal insulation, support, and positioning functions into four core components, avoiding the difficulties in processing and assembly caused by overly complex structures. Furthermore, through detailed design details such as optimized curvature of the crests and troughs and controlled depth of the positioning grooves, an optimal balance between thermal insulation and mechanical properties is achieved. Compared to existing technologies, it offers significant advantages such as improved thermal insulation, compact and reliable structure, convenient installation and maintenance, and long service life. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a heat-insulating bridge structure for a measuring tube;

[0029] Figure 2 This is a cross-sectional view of a measuring tube heat insulation bridge structure;

[0030] Figure 3 This is a side view of a measuring tube thermal bridge structure;

[0031] The attached diagram lists the components represented by each number as follows:

[0032] 1. Annular support base; 2. Bridging arm; 3. Thermal insulation layer. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0034] like Figures 1-3 The diagram shows a first embodiment of a heat-insulating bridge structure for a measuring tube provided by this utility model. In this embodiment, it is used to connect the inner and outer parts of the measuring tube and includes an annular support 1, a bridging arm 2, a thermally conductive blocking layer 3, and a fixing ring. The annular support is disposed on the inner wall of the measuring tube. The first end of the bridging arm is connected to the outer circumferential surface of the annular support, and the second end of the bridging arm extends to the outer wall of the measuring tube. The thermally conductive blocking layer covers the outer surface of the bridging arm, and the fixing ring is sleeved on the outer side of the second end of the bridging arm. The fixing ring is interference-fitted with the outer wall of the measuring tube. The bridging arm has a wavy structure in its axial cross-section. The wavy structure has at least three peaks and two troughs arranged alternately. The thermally conductive blocking layer is tightly attached to the wavy outer surface of the bridging arm.

[0035] In the above technical solution, the inner circumferential surface of the annular support is provided with multiple radial reinforcing ribs, which are evenly distributed along the circumference of the annular support. The radial height of the radial reinforcing ribs decreases from the inner circumferential surface of the annular support towards the geometric center.

[0036] Furthermore, in the above technical solution, the radius of curvature at the crest of the bridging arm is smaller than the radius of curvature at the trough of the bridging arm, and the transition section between the crest and the trough is a smooth curved surface connection.

[0037] Furthermore, in the above technical solution, a spiral groove is provided on the inner circumferential surface of the fixing ring, the spiral helix angle of the spiral groove is the ratio of the axial length of the fixing ring to its circumference, and a clearance fit is formed between the bottom of the spiral groove and the outer surface of the second end of the bridging arm.

[0038] Furthermore, in the above technical solution, the thermally conductive blocking layer has a multi-layered concentric ring structure in cross-section. The multi-layered concentric ring structure consists of a first blocking layer, a second blocking layer, and a third blocking layer from the inside out, and the layers are connected by an adhesive method.

[0039] Furthermore, in the above technical solution, an annular boss is provided on the outer peripheral surface of the annular support base, the end face of the first end of the bridging arm abuts against the side of the annular boss, and the first end of the bridging arm is fixed to the side of the annular boss by welding.

[0040] Furthermore, in the above technical solution, the number of wave crests in the wave-shaped structure of the bridging arm is three, the axial spacing between two adjacent wave crests is equal, and the depth of the wave trough is 1 / 5 to 1 / 4 of the total axial length of the bridging arm.

[0041] Furthermore, in the above technical solution, the outer circumferential surface of the fixing ring is provided with a plurality of axially distributed positioning grooves, the groove openings of the positioning grooves facing the radial outer side of the fixing ring, and the groove depth of the positioning grooves being 1 / 3 to 1 / 2 of the wall thickness of the fixing ring.

[0042] Furthermore, in the above technical solution, the bridging arm is made of stainless steel, the thermally insulating layer is made of polytetrafluoroethylene, and the annular support and fixing ring are both made of aluminum alloy.

[0043] Furthermore, in the above technical solution, the end face of the second end of the bridging arm is provided with an annular groove, and the inner circumferential surface of the fixing ring is provided with an annular protrusion that mates with the annular groove at a corresponding position. The annular protrusion is embedded in the annular groove to form an axial limiting fit.

[0044] The following is a specific embodiment 1 of this utility model. In this embodiment, the measuring tube heat-insulating bridge structure is applied to a high-temperature reactor temperature measuring system in a petrochemical plant. The internal process medium temperature of the measuring tube is 450℃, and the external ambient temperature is 25℃. The annular support is made of 6061 aluminum alloy, with an outer diameter of 48mm, an inner diameter of 36mm, and an axial height of 15mm. Six radial reinforcing ribs are evenly arranged circumferentially on the inner circumferential surface of the annular support. The circumferential width of each radial reinforcing rib is 8mm, and the radial height linearly decreases from 5mm on the inner circumferential surface towards the geometric center to 2mm. The included angle between adjacent reinforcing ribs is 60°. The bridging arm is made of 304 stainless steel and has a slender, wave-shaped plate structure with a total axial length of 85mm. Its axial cross-section features three alternating peaks and two troughs. Each peak has a top curvature radius of 4mm, and each trough has a bottom curvature radius of 8mm. The peaks and troughs are smoothly transitioned by a curved surface with a radius of 12mm. The maximum depth of the troughs is 18mm, and the axial spacing between adjacent peaks is 28mm. The bridging arm has a rectangular cross-section with a width of 10mm and a thickness of 3mm. The first end of the bridging arm is fixed to an annular boss on the outer circumference of the annular support base via argon arc welding. The annular boss has a radial height of 4mm and an axial width of 8mm. The weld joint uses a fillet weld with a weld height of 2mm. The thermally insulating layer consists of three layers of polytetrafluoroethylene (PTFE). The first insulating layer is 1.5 mm thick, the second is 2 mm thick, and the third is 1.5 mm thick. The layers are bonded together using a 0.2 mm thick silicone high-temperature resistant adhesive. The thermally insulating layer completely covers the wavy outer surface of the bridging arm, maintaining a uniform thickness at both the crests and troughs. The retaining ring is made of 6061 aluminum alloy, with an inner diameter of 24 mm, an outer diameter of 32 mm, and an axial length of 20 mm. A single-headed spiral groove is provided on the inner circumference of the retaining ring, with a groove width of 3 mm and a groove depth of 2 mm. The helix angle is the ratio of the axial length of 20 mm to the inner circumference of 75 mm. Four positioning grooves are evenly distributed along the axial direction on the outer circumference of the retaining ring, with a groove width of 5 mm, a groove depth of 3 mm, and an axial length of 12 mm. An annular groove is provided on the end face of the second end of the bridging arm. The groove is 2.5 mm wide and 1.8 mm deep. An annular protrusion is provided on the inner circumference of the fixing ring at the corresponding position. The protrusion is 2.3 mm wide and 1.6 mm high. The two fit together to form a clearance fit of 0.2 mm.The working principle of the entire thermal bridge structure is as follows: when the high-temperature medium inside the measuring tube heats the annular support, the heat is transferred outward through the bridging arm. Due to the tortuous path of the wavy structure and the blocking effect of the multi-layer thermally conductive blocking layer, the heat flux density is greatly reduced. Calculations show that the wavy bridging arm increases the heat flux path length from a straight distance of 85mm to an actual path length of approximately 145mm. Combined with the low thermal conductivity of the PTFE blocking layer, the overall thermal resistance value is more than 8 times that of a single-layer straight structure, effectively reducing the temperature of the outer wall of the measuring tube and reducing heat loss. At the same time, the radial reinforcing ribs of the annular support evenly distribute the thermal stress, and the interference fit of the fixing ring and the axial limiting effect of the annular groove protrusion work together to ensure the stability of the structure under thermal cycling conditions. Practical applications show that the thermal bridge structure has stable and reliable performance and meets the requirements for use in high-temperature measurement environments.

[0045] The following is another specific embodiment 2 of this utility model. Embodiment 2 is an improvement on Embodiment 1, designed for higher temperature conditions, and is suitable for temperature measurement in high-temperature molten salt reactors with process media temperatures reaching 650℃. In this embodiment, the wave-shaped structure of the bridging arm has been optimized and adjusted. The number of wave crests has increased to 5, and the number of wave troughs has increased accordingly to 4. The radius of curvature at the top of the wave crest has decreased to 3mm, while the radius of curvature at the bottom of the wave trough remains unchanged at 8mm. The axial spacing between adjacent wave crests has been shortened to 18mm, and the total axial length of the bridging arm has increased to 95mm. This adjustment further extends the heat transfer path, with the actual path length reaching approximately 185mm. The thermally insulating layer has been increased to a four-layer structure, with a thin ceramic fiber layer added between the original three polytetrafluoroethylene layers. The ceramic fiber layer is 1mm thick, exhibiting higher temperature resistance and lower thermal conductivity. The total thickness of the four-layer structure reaches 7mm, improving the overall thermal insulation performance by approximately 40%. The number of radial stiffeners in the annular support has been increased to eight, with the radial height of each stiffener decreasing from 6 mm to 2 mm. This increased number of stiffeners further enhances the support rigidity, better enabling it to withstand increased thermal stress under high-temperature conditions. The fixing ring is now made of high-temperature resistant titanium alloy, which maintains excellent mechanical properties and oxidation resistance at high temperatures. The number of positioning grooves on the outer circumference of the fixing ring has been increased to six, and the groove depth has been increased to 4 mm, providing more reliable external fixing capabilities. The depth of the annular groove at the second end of the bridging arm has been increased to 2.5 mm, and the height of the annular protrusion of the fixing ring has been correspondingly increased to 2.2 mm, while maintaining a 0.3 mm clearance, thus enhancing the axial limiting effect. This embodiment extends the heat flow path by increasing the number of crests and troughs, increases the number of blocking layers to improve thermal resistance, and uses high-temperature resistant materials to improve structural reliability, achieving stable operation under 650℃ high-temperature conditions and meeting more stringent usage requirements.

[0046] The following is another specific embodiment 3 of this utility model. Embodiment 3 is an optimized design based on Embodiment 1, specifically for cryogenic conditions, and is suitable for cryogenic measurement environments where the process medium temperature in liquefied natural gas storage tanks is -160℃. In this embodiment, the bridging arm material is changed to 316L stainless steel, which has superior toughness and impact resistance in low-temperature environments, avoiding the risk of cryogenic brittle fracture. The wavy structure of the bridging arm maintains 3 peaks and 2 troughs, but the radius of curvature at the top of the peaks is increased to 6mm, and the radius of curvature at the bottom of the troughs is increased to 10mm. This adjustment ensures that the bridging arm maintains sufficient elastic deformation capacity during low-temperature contraction, avoiding cracking caused by stress concentration. The thermally insulating layer uses modified polytetrafluoroethylene (PTFE), which, after special treatment, maintains good flexibility at low temperatures and will not become brittle due to temperature reduction. The thicknesses of the three insulating layers are adjusted to 2mm, 2.5mm, and 2mm respectively, with a total thickness of 6.5mm. The layers are connected using a low-temperature flexible adhesive to ensure that the layers do not peel off during drastic temperature changes. Both the annular support and the fixing ring are made of 5083 aluminum alloy, which exhibits increased strength without reduced toughness at low temperatures, meeting the requirements of low-temperature operating conditions. The spiral groove depth of the fixing ring is reduced to 1.5mm to prevent excessively deep grooves from weakening the overall strength of the fixing ring at low temperatures. The welding of the first end of the bridging arm to the annular support uses a low-temperature welding process, followed by low-temperature annealing to eliminate residual welding stress and improve the low-temperature toughness of the weld joint. This embodiment, by selecting materials with excellent low-temperature performance, optimizing the curvature parameters of the corrugated structure, and employing a low-temperature flexible bonding process, achieves reliable thermal insulation and long-term stable operation under -160℃ low-temperature conditions, effectively solving the problems of thermal insulation and stress control in low-temperature measurement environments.

[0047] Specifically, the principle of this invention is as follows: through the synergistic effect of the corrugated bridging arm and the multi-layer thermally insulating layer, a highly efficient thermal resistance network is constructed between the inner and outer sides of the measuring tube, thereby significantly reducing the heat transfer rate and dispersing thermal stress. When the inside of the measuring tube is at a high temperature, heat is transferred from the annular support to the bridging arm. Due to the corrugated structure of the bridging arm, the heat flow cannot be transferred along a straight path, but is forced to travel along a tortuous path of crests and troughs. This tortuous path significantly increases the heat transfer distance. According to the law of thermal conductivity, under the same material and temperature difference conditions, the longer the transfer path, the greater the thermal resistance. Therefore, the corrugated structure geometrically increases the thermal resistance. The multi-layer thermally insulating layer covering the outer surface of the bridging arm further enhances the thermal insulation effect. Polytetrafluoroethylene (PTFE) material itself has an extremely low thermal conductivity, only a few thousandths that of stainless steel. The multi-layer concentric ring structure requires heat to cross the material interface multiple times during the transfer process. Each crossing generates interfacial thermal resistance at the interface. The cumulative effect of the multi-layer structure causes the total thermal resistance to increase exponentially. The interference fit between the fixing ring and the outer wall of the measuring tube creates a radial pre-stress. This pre-stress offsets some of the thermal stress generated by the temperature gradient, reducing the stress level of the measuring tube wall. Simultaneously, the annular groove at the second end of the bridging arm and the annular protrusion of the fixing ring form a mechanical lock, preventing relative displacement caused by thermal expansion. Radial reinforcing ribs on the annular support evenly distribute the thermal stress from the inner wall of the measuring tube to multiple reinforcing ribs, avoiding stress concentration at a single point. The design of decreasing rib height ensures a smooth transition of stiffness from the outer periphery to the center, preventing stress concentration caused by abrupt changes in stiffness. The working principle of the entire structure can be understood as a dual mechanism of thermal resistance series connection and stress dispersion. The total thermal resistance formed by the wavy bridging arm and multiple blocking layers is much greater than the sum of the thermal resistances of each part, while the multi-point support and gradually varying stiffness design effectively disperse thermal stress. This design philosophy ensures that the thermal bridge structure can significantly reduce heat flux density and withstand long-term thermal cycling loads without fatigue failure.

[0048] The specific operation or use method of this utility model is as follows: First, the annular support seat is installed at a predetermined position on the inner wall of the measuring tube. A firm connection is formed between the annular support seat and the inner wall of the measuring tube through welding or threaded connection, ensuring that the geometric center of the annular support seat coincides with the central axis of the measuring tube. Then, the first end of the bridging arm is aligned with the annular boss on the outer circumference of the annular support seat, ensuring that the end face of the bridging arm is completely fitted with the side of the boss. The bridging arm is welded and fixed to the annular boss using argon arc welding or laser welding. During the welding process, the welding heat input is controlled to avoid overheating and deformation of the bridging arm. Next, the first blocking layer, the second blocking layer, and the third blocking layer are sequentially wrapped around the wavy outer surface of the bridging arm. A high-temperature resistant adhesive is applied between each layer to ensure a tight fit without air gaps. During the wrapping process, care is taken to ensure that the thermally conductive blocking layer fits tightly against the curved surfaces of the crests and troughs to avoid wrinkles or voids. Then… Guided by the spiral groove, the retaining ring is gradually fitted onto the outer side of the second end of the bridging arm. During the fitting process, the annular protrusion of the retaining ring is aligned with the annular groove at the second end of the bridging arm. After the annular protrusion is fully embedded in the annular groove, the retaining ring is pressed into the predetermined position on the outer wall of the measuring tube by hydraulic or mechanical pressure. Reliable fixation is achieved by utilizing the elastic deformation force generated by the interference fit between the retaining ring and the outer wall of the measuring tube. After installation, the entire thermal bridge structure is visually inspected and tested for air tightness to confirm that there are no cracks or leaks at any connection. Before being put into use, a thermal cycling test is conducted, in which the measuring tube is heated from room temperature to the working temperature and then cooled back to room temperature. After several cycles, the thermal bridge structure is checked for loosening or damage. Only after passing the test can it be officially put into production. During daily use, the positioning groove on the outer circumference of the retaining ring and all connection parts are checked regularly. If any abnormalities are found, maintenance or replacement should be carried out in a timely manner.

Claims

1. A thermal bridge structure for a measuring tube, used to connect an inner portion and an outer portion of a measuring tube, comprising an annular support, a bridging arm, a thermally insulating layer, and a fixing ring; the annular support is disposed on the inner wall of the measuring tube, a first end of the bridging arm is connected to the outer circumferential surface of the annular support, a second end of the bridging arm extends to the outer wall of the measuring tube, the thermally insulating layer covers the outer surface of the bridging arm, and the fixing ring is sleeved on the outer side of the second end of the bridging arm, the fixing ring being interference-fitted with the outer wall of the measuring tube, characterized in that... The bridging arm has a wavy structure in its axial cross-section, and the wavy structure has at least three peaks and two troughs arranged alternately. The thermally conductive barrier layer is closely attached to the wavy outer surface of the bridging arm.

2. The measuring tube heat insulation bridge structure according to claim 1, characterized in that, The inner circumferential surface of the annular support is provided with a plurality of radial reinforcing ribs, which are evenly distributed along the circumference of the annular support, and the radial height of the radial reinforcing ribs decreases from the inner circumferential surface of the annular support towards the geometric center.

3. The measuring tube heat insulation bridge structure according to claim 2, characterized in that, The radius of curvature at the crest of the bridging arm is smaller than the radius of curvature at the trough of the bridging arm, and the transition section between the crest and the trough is a smooth curved surface connection.

4. The measuring tube heat insulation bridge structure according to claim 3, characterized in that, The inner circumferential surface of the fixing ring is provided with a spiral groove, the spiral helix angle of the spiral groove is the ratio of the axial length of the fixing ring to its circumference, and the bottom of the spiral groove forms a clearance fit with the outer surface of the second end of the bridging arm.

5. The measuring tube heat insulation bridge structure according to claim 4, characterized in that, The thermally conductive blocking layer has a multi-layered concentric ring structure in cross-section. The multi-layered concentric ring structure consists of a first blocking layer, a second blocking layer, and a third blocking layer from the inside out. The layers are connected by adhesive bonding.

6. The measuring tube heat insulation bridge structure according to claim 5, characterized in that, The outer circumferential surface of the annular support is provided with an annular boss, and the end face of the first end of the bridging arm abuts against the side of the annular boss. The first end of the bridging arm is fixed to the side of the annular boss by welding.

7. The measuring tube heat insulation bridge structure according to claim 6, characterized in that, The bridging arm has three wave crests in its wave-shaped structure, with equal axial spacing between adjacent crests, and the depth of the troughs is 1 / 5 to 1 / 4 of the total axial length of the bridging arm.

8. The measuring tube heat insulation bridge structure according to claim 7, characterized in that, The outer circumferential surface of the fixed ring is provided with a plurality of axially distributed positioning grooves, the groove openings of the positioning grooves facing the radially outer side of the fixed ring, and the groove depth of the positioning grooves being 1 / 3 to 1 / 2 of the wall thickness of the fixed ring.

9. A measuring tube heat insulation bridge structure according to claim 8, characterized in that, The bridging arm is made of stainless steel, the thermally insulating layer is made of polytetrafluoroethylene, and the annular support and the fixing ring are both made of aluminum alloy.

10. A measuring tube heat insulation bridge structure according to claim 9, characterized in that, The end face of the second end of the bridging arm is provided with an annular groove, and the inner circumferential surface of the fixing ring is provided with an annular protrusion that mates with the annular groove. The annular protrusion is embedded in the annular groove to form an axial limiting fit.

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