A surface temperature measuring device for ultra-low temperature pipelines adopting a pipe hoop structure

Abstract

The present invention relates to a surface temperature measurement device for cryogenic pipelines using a pipe clamp structure, which includes a pipe clamp, connecting bolts, limit bolts, a temperature measurement block and a temperature measurement element; the pipe clamp is fixed on the periphery of the cryogenic pipeline through the connecting bolts, and at least one temperature measurement block is arranged between the pipe clamp and the cryogenic pipeline. One surface of the temperature measurement block in contact with the cryogenic pipeline is an arc surface, and the two side surfaces in contact with the pipe clamp are inclined surfaces that incline towards the outside and the center of the cryogenic pipeline; the arc surface has a radian that matches the outer surface of the cryogenic pipeline; a cavity is provided on the temperature measurement block for placing the temperature measurement element. The temperature measurement device of the present invention is detachably connected to the cryogenic pipeline, does not require opening holes and welding operations on the cryogenic pipeline, and can monitor the temperature difference between the upper and lower surfaces of the cryogenic pipeline for pre-cooling, preventing the occurrence of the "banana effect".

Description

Technical Field

[0001] The present invention relates to the technical field of cryogenic measurement for cryogenic pipelines, and particularly to a device for measuring the surface temperature of cryogenic pipelines with a temperature range from -100°C to -273°C. Background Art

[0002] At present in China, pipelines are classified according to their working temperatures. Generally, pipelines with a medium working temperature below -40°C are called cryogenic pipelines, and those with a medium working temperature below -100°C are called ultra-cryogenic pipelines. According to this definition, the common working media of ultra-cryogenic pipelines mainly include: liquid hydrogen, liquid nitrogen, liquid oxygen, and liquefied natural gas (LNG).

[0003] Due to the good cryogenic properties of stainless steel and 9% nickel steel, they are widely used in cryogenic engineering. Considering material properties, economic applicability, and application maturity, stainless steel is more widely used in cryogenic engineering pipelines.

[0004] Due to the hazards contained in ultra-cryogenic working media during transportation and transfer, the surface temperature monitoring of ultra-cryogenic pipelines is an important part of the operation monitoring of cryogenic industrial facility pipe network systems. Currently, there are mainly three common ultra-cryogenic temperature measuring elements: thermocouples, diodes, and resistance cables. These three temperature measuring elements have different temperature measuring principles and physical characteristics in ultra-cryogenic environments, and thus have different advantages, disadvantages, and application ranges.

[0005] Thermocouple temperature measuring elements generally have medium accuracy and relatively small errors, and are the most widely used.

[0006] Diode temperature measuring elements have high accuracy, slightly larger errors, a very low temperature measuring lower limit, and a service life lower than the other two temperature measuring elements.

[0007] Resistance cables have a temperature measuring accuracy and error between those of thermocouples and diodes, and a higher temperature measuring lower limit than the former two. The resistance cables are wound around the outer wall of the pipeline for measurement, and the obtained temperature value is the average temperature of the pipeline in the circumferential direction; when there is gas-liquid separation in the ultra-cryogenic pipeline and during the pre-cooling operation of the ultra-cryogenic pipeline, the resistance cables are not suitable for temperature measurement.

[0008] Traditional methods for monitoring the surface temperature of ultra-cryogenic pipelines are as follows: Determine the temperature measuring positions on the selected pipeline, open a groove on the outer wall of the pipeline at a certain inclination angle, weld a shell-shaped steel plate at the corresponding inner wall position of the pipeline, and wrap the range where the groove is located in a sealed manner, so as to form a cavity isolated from the working medium inside the pipeline at the inner wall of the pipeline opening position. Place the temperature measuring element within this cavity, supply a 5 - 12V DC power supply through a cable, and send the obtained electrical signal out through a signal line.

[0009] The above-mentioned ultra-low temperature pipeline temperature measurement method has the following deficiencies:

[0010] 1. Since the fire and explosion prevention grades of liquid hydrogen, liquid oxygen, and LNG plants and stations are relatively high, cutting and welding of pipelines are not allowed at the engineering site, and only pipe opening and welding can be carried out on the pipelines in the equipment processing factory. Therefore, the selection of temperature measurement points on the pipeline is greatly limited, and once the temperature measurement points are determined, they cannot be adjusted.

[0011] 2. Since the material of ultra-low temperature pipelines is different from that of ordinary carbon steel, the welding performance is relatively poor; for pipelines with the same DN diameter, the wall thickness of ultra-low temperature pipelines is several times that of ordinary carbon steel pipelines. Therefore, when opening holes and welding ultra-low temperature pipelines, special electrodes and special welders are required. After welding on the inner wall of the pipeline, leak detection operations need to be carried out. The above processes significantly increase the labor cost.

[0012] In addition, for equipment and pipelines storing and transporting ultra-low temperature working media, pre-cooling operations are required when resuming production after commissioning and maintenance. When pre-cooling ultra-low temperature pipelines, due to the temperature difference generated between the upper and lower parts of the pipeline during the transmission and phase change of the pre-cooling working medium, when this temperature difference reaches a certain value, it will cause the "banana effect" of the pipeline, which will further lead to irreversible and uncontrollable bending deformation, resulting in serious economic losses and safety accidents. By monitoring the upper and lower surface temperatures of the ultra-low temperature pipeline at different positions during the pre-cooling process, real-time intervention can be carried out on the pre-cooling process to avoid the occurrence of the "banana effect". By comparing the temperature differences between the upper and lower surfaces of the ultra-low temperature pipeline at the same position, it helps to precisely control the pre-cooling process and minimize the probability of accidents and economic losses to the greatest extent. Summary of the Invention

[0013] The present invention provides an ultra-low temperature pipeline surface temperature measurement device using a pipe hoop structure. The temperature measurement device is detachably connected to the ultra-low temperature pipeline, does not require pipe opening and welding operations on the ultra-low temperature pipeline, and can monitor the temperature difference between the upper and lower surfaces of the ultra-low temperature pipeline for pre-cooling to prevent the occurrence of the "banana effect".

[0014] To achieve the above object, the present invention is realized by the following technical solutions:

[0015] An ultra-low temperature pipeline surface temperature measurement device using a pipe hoop structure includes a pipe hoop, connecting bolts, limit bolts, a temperature measurement block, and a temperature measurement element; the pipe hoop is fixed around the ultra-low temperature pipeline through the connecting bolts, at least one temperature measurement block is provided between the pipe hoop and the ultra-low temperature pipeline, one surface of the temperature measurement block in contact with the ultra-low temperature pipeline is an arc surface, and the two side surfaces in contact with the pipe hoop are inclined planes inclined towards the outside and the center of the ultra-low temperature pipeline; the arc surface has a radian matching the outer surface of the ultra-low temperature pipeline; a cavity is opened on the temperature measurement block for placing the temperature measurement element.

[0016] The pipe clamp is an annular pipe clamp. Connection segments are respectively arranged at both ends of the annular pipe clamp. The connection segment is composed of an inclined segment that cooperates with the upper inclined surface of the temperature measuring block and a straight segment for mating connection; the limit bolt is arranged at the straight segment close to the inclined segment, and the connection bolt is arranged at the straight segment far from the inclined segment.

[0017] A hinge is arranged in the middle of the annular pipe clamp.

[0018] The pipe clamp is composed of 2 symmetrical semi-annular pipe clamps; connection segments are respectively arranged at both ends of the semi-annular pipe clamp. The connection segment is composed of an inclined segment that cooperates with the upper inclined surface of the temperature measuring block and a straight segment for mating connection; the limit bolt is arranged at the straight segment close to the inclined segment, and the connection bolt is arranged at the straight segment far from the inclined segment.

[0019] The temperature measuring element is connected to a DC power supply through a power line and is connected to a temperature display instrument or a control system through a signal line.

[0020] The pipe clamp, connection bolt, limit bolt and temperature measuring block are all made of low-temperature resistant alloy steel.

[0021] One temperature measuring block is respectively arranged on the top surface and the bottom surface of the cryogenic pipeline. The signal lines of the temperature measuring elements in the 2 temperature measuring blocks are respectively connected to the signal input ends of a logic arithmetic unit, and the signal output end of the logic arithmetic unit is connected to an alarm or a control system.

[0022] An opening is arranged at one end of the cavity in the temperature measuring block corresponding to the axial direction of the cryogenic pipeline.

[0023] The temperature measuring element is a thermocouple or a diode.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1) The temperature measuring device of the present invention is convenient for disassembly and movement, can measure the surface temperature at different positions along the circumferential direction of the cryogenic pipeline, can be moved and adjusted along the radial direction of the cryogenic pipeline, and can also measure the surface temperature at different pipeline lengths; compared with conventional similar measuring devices, the adaptability to different working conditions and different process requirements is fundamentally improved.

[0026] 2) The temperature measuring device of the present invention adopts a detachable connection method with the cryogenic pipeline, does not require opening holes and welding operations on the cryogenic pipeline, and basically does not require welding operations during the manufacturing process. Therefore, the consumption amount, workload of special welding and the requirements for welders are fundamentally reduced;

[0027] 3) It is convenient to replace the temperature measuring element. For the cryogenic pipeline for precooling, a logic arithmetic unit is used to calculate the temperature difference between the upper and lower surfaces, and an alarm signal is sent based on the calculation result and logical judgment;

[0028] 4) The overall structure is simple, with low manufacturing cost and safe and reliable use; it is especially suitable for large LNG plants and can play a key role in improving the temperature monitoring of cryogenic pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic structural diagram of the cryogenic pipeline surface temperature measuring device in Embodiment 1 of the present invention.

[0030] Figure 2 is Figure 1 a side view of

[0031] Figure 3a It is a front view of the annular pipe clamp in Embodiment 1 of the present invention.

[0032] Figure 3b is Figure 3a a side view of

[0033] Figure 4 It is a schematic structural diagram of the cryogenic pipeline surface temperature measuring device in Embodiment 2 of the present invention.

[0034] Figure 5 is Figure 4 a side view of

[0035] Figure 6a It is a front view of the semi-annular pipe clamp in Embodiment 2 of the present invention.

[0036] Figure 6b is Figure 6a a side view of

[0037] Figure 7a It is a front view of the temperature measuring block described in the present invention.

[0038] Figure 7b It is a top view of the temperature measuring block described in the present invention.

[0039] In the figure: 1. Pipe clamp 11. Annular pipe clamp 12. Semi-annular pipe clamp 2. Connecting bolt 3. Limit bolt 4. Temperature measuring block 41. Cavity 42. Arc surface 43. Inclined surface 5. Temperature measuring element 6. Logic operation unit 7. Cryogenic pipeline 8. Hinge DETAILED DESCRIPTION OF THE INVENTION

[0040] The following further describes the specific embodiments of the present invention with reference to the drawings:

[0041] As shown in Figure 1 , Figure 2 , Figure 4 , Figure 5As shown in the figure, the ultra-low temperature pipeline surface temperature measuring device adopting a pipe hoop structure according to the present invention includes a pipe hoop 1, connecting bolts 2, limiting bolts 3, a temperature measuring block 4 and a temperature measuring element 5; the pipe hoop 1 is fixed on the periphery of the ultra-low temperature pipeline 7 through the connecting bolts 2, and at least one temperature measuring block 4 is arranged between the pipe hoop 1 and the ultra-low temperature pipeline 7. One surface of the temperature measuring block 4 in contact with the ultra-low temperature pipeline 7 is an arc surface 42, and the two side surfaces in contact with the pipe hoop 1 are inclined surfaces 43 inclined towards the outside and the center of the ultra-low temperature pipeline 7; the arc surface 42 has a radian matching the outer surface of the ultra-low temperature pipeline 7; a cavity 41 is opened on the temperature measuring block 4 for placing the temperature measuring element 5.

[0042] As Figure 1 , Figure 2 , Figure 3a , Figure 3b shown in the figure, the pipe hoop 1 is an annular pipe hoop 11, and connecting sections are respectively arranged at both ends of the annular pipe hoop 11. The connecting section is composed of an inclined section matching the inclined surface 43 on the temperature measuring block 4 and a straight section for fitting connection; the limiting bolt 3 is arranged at the straight section close to the inclined section, and the connecting bolt 2 is arranged at the straight section far from the inclined section.

[0043] A hinge 8 is arranged in the middle of the annular pipe hoop 11.

[0044] As Figure 4 , Figure 5 , Figure 6a , Figure 6b shown in the figure, the pipe hoop 1 is composed of two symmetrical semi-annular pipe hoops 12; connecting sections are respectively arranged at both ends of the semi-annular pipe hoop 12. The connecting section is composed of an inclined section matching the inclined surface on the temperature measuring block 4 and a straight section for fitting connection; the limiting bolt 3 is arranged at the straight section close to the inclined section, and the connecting bolt 2 is arranged at the straight section far from the inclined section.

[0045] As Figure 2 shown in the figure, the temperature measuring element 5 is connected to a DC power supply through a power line and connected to a temperature display instrument or a control system through a signal line.

[0046] The pipe hoop 1, the connecting bolts 2, the limiting bolts 3 and the temperature measuring block 4 are all made of low-temperature resistant alloy steel.

[0047] As Figure 5 shown in the figure, one temperature measuring block 4 is respectively arranged on the top surface and the bottom surface of the ultra-low temperature pipeline 7, and the signal lines of the temperature measuring elements 5 in the two temperature measuring blocks 4 are respectively connected to the signal input ends of a logic arithmetic unit 6, and the signal output end of the logic arithmetic unit 6 is connected to an alarm or a control system.

[0048] As Figure 7a , Figure 7b shown in the figure, an opening is arranged at one end of the cavity 41 in the temperature measuring block 4 corresponding to the axial direction of the ultra-low temperature pipeline 7.

[0049] The temperature measuring element 5 is a thermocouple or a diode.

[0050] The following embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The methods used in the following embodiments are all conventional methods unless otherwise specified.

[0051]

Embodiment 1

[0052] In this embodiment, a cryogenic pipeline surface temperature measuring device with a pipe clamp structure is adopted, which includes an annular locking structure formed by an annular pipe clamp 11, a connecting bolt 2 and a limiting bolt 3 for restricting the movement of the temperature measuring block 4. One temperature measuring block 4 is provided, and the limiting bolt 3 forces the temperature measuring block 4 to fit and fix on the top of the outer surface of the cryogenic pipeline 7. The connecting bolt 2 and the limiting bolt 3 jointly play a connecting role and provide more safety constraints to prevent the annular pipe clamp 11 from failing in the cryogenic environment and causing the temperature measuring block 4 to fall off.

[0053] A hinge 8 is provided in the middle of the annular pipe clamp 11 to facilitate the opening, disassembly and movement of the annular pipe clamp 11. Four bolt holes are respectively opened at the connecting ends on both sides of the annular pipe clamp 11 for the limiting bolt 3 and the connecting bolt 2 to pass through.

[0054] A cavity 41 is provided inside the temperature measuring block 4, and the temperature measuring element 5 is installed and fixed in the cavity 41 during application. The temperature measuring element 5 is connected with a power line and a signal line for externally transmitting the obtained temperature signal. Further, the temperature signal can be transmitted outward by wired or wireless means, that is, the temperature signal transmission method using wireless means is also within the protection scope of the present invention.

[0055] The annular pipe clamp 11, the connecting bolt 2, the limiting bolt 3 and the temperature measuring block 4 are all made of alloy steel with good low-temperature performance. After the cryogenic pipeline surface temperature measuring device is installed, relevant operations need to be carried out according to the heat preservation requirements of the cryogenic pipeline.

[0056]

Embodiment 2

[0057] In this embodiment, the cryogenic pipeline surface temperature measuring device is used to measure the temperature of the upper and lower surfaces of the cryogenic pipeline for precooling. The device includes an annular locking structure formed by a semi-circular pipe clamp 12, a connecting bolt 2 and a limiting bolt 3 for restricting the movement of two temperature measuring blocks 4 arranged on the upper and lower surfaces of the cryogenic pipeline 7. The limiting bolt 3 forces the temperature measuring blocks 4 to fit and fix on one side of the outer surface of the cryogenic pipeline 7. The connecting bolt 2 and the limiting bolt 3 jointly play a connecting role and provide more safety constraints to prevent the annular pipe clamp 11 from failing in the cryogenic environment and causing the temperature measuring blocks 4 to fall off.

[0058] The semi-circular pipe clamps 12 are grouped in pairs of two and are butted together relatively, which is convenient for opening, disassembling and moving, and also convenient for replacing the temperature measuring block 4. Four bolt holes are provided at each connecting section at both ends of the semi-circular pipe clamp 12 for the connecting bolts 2 and the limit bolts 3 to pass through.

[0059] A cavity 41 is provided inside the temperature measuring block 4. During temperature measurement, the temperature measuring element 5 is installed and fixed in the cavity 41. The temperature measuring element 5 is connected with a power line and a signal line, and sends the obtained temperature signal to the logic arithmetic unit 6 for processing during temperature measurement. After receiving the temperature signals from two temperature measuring elements 5, the logic arithmetic unit 6 calculates the temperature difference between the upper and lower surfaces of the cryogenic pipeline. When this difference is greater than the limit judgment value (5 - 10 °C), an alarm signal is sent. The specific limit judgment value is related to the diameter of the cryogenic pipeline 7. As the diameter of the cryogenic pipeline 7 increases, this limit value also increases accordingly. The maximum temperature difference between the upper and lower surfaces of the cryogenic pipeline 7 cannot exceed 10 °C, otherwise the cryogenic pipeline undergoing pre-cooling operation will bend and be damaged due to the "banana effect".

[0060] The alarm mode after the logic arithmetic unit 6 sends an alarm signal can adopt different methods such as sound and light, and the logic arithmetic unit 6 can also choose to send the alarm signal to the remote control room in a wired or wireless manner.

[0061] The semi-circular pipe clamps 12, the connecting bolts 2, the limit bolts 3 and the temperature measuring blocks 4 are all made of alloy steel with good low-temperature performance. After the surface temperature measuring device of the cryogenic pipeline is installed, relevant operations need to be carried out according to the heat preservation requirements of the cryogenic pipeline.

[0062] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. An ultra-low temperature pipeline surface temperature measurement device using a pipe hoop structure, characterized in that, It includes a pipe clamp, connecting bolts, limit bolts, temperature measuring blocks and temperature measuring elements; the pipe clamp is fixed on the periphery of the cryogenic pipeline through the connecting bolts, a temperature measuring block is arranged between the pipe clamp and the cryogenic pipeline, one temperature measuring block is arranged on each of the top surface and the bottom surface of the cryogenic pipeline, the surface of the temperature measuring block in contact with the cryogenic pipeline is an arc surface, and the two side surfaces in contact with the pipe clamp are inclined surfaces inclined towards the outside and the center of the cryogenic pipeline; the arc surface has a radian matching the outer surface of the cryogenic pipeline; the pipe clamp is an annular pipe clamp, a hinge is arranged in the middle of the annular pipe clamp, connecting sections are respectively arranged at both ends of the annular pipe clamp, and the connecting section is composed of an inclined section matching the inclined surface on the temperature measuring block and a straight section for fitting connection; the limit bolt is arranged at the straight section close to the inclined section, and the connecting bolt is arranged at the straight section far from the inclined section; a cavity is formed in the temperature measuring block for placing the temperature measuring element; the signal lines of the temperature measuring elements in the two temperature measuring blocks are respectively connected to the signal input ends of the logic operation unit, and the signal output end of the logic operation unit is connected to an alarm or a control system; during the temperature measurement process, the obtained temperature signals are sent to the logic operation unit for processing, after the logic operation unit receives the temperature signals from the temperature measuring elements, it calculates the temperature difference between the upper and lower surfaces of the cryogenic pipeline, and when this difference is greater than the limit judgment value, an alarm signal is sent out.

2. The ultra-low temperature pipeline surface temperature measurement device using a pipe hoop structure according to claim 1, characterized in that, The pipe clamp is composed of two symmetrical semi-annular pipe clamps; connecting sections are respectively arranged at both ends of the semi-annular pipe clamp, and the connecting section is composed of an inclined section matching the inclined surface on the temperature measuring block and a straight section for fitting connection; the limit bolt is arranged at the straight section close to the inclined section, and the connecting bolt is arranged at the straight section far from the inclined section.

3. The ultra-low temperature pipeline surface temperature measurement device using a pipe hoop structure according to claim 1, characterized in that, The temperature measuring element is connected to a DC power supply through a power line and connected to a temperature display instrument or a control system through a signal line.

4. The ultra-low temperature pipeline surface temperature measurement device using a pipe hoop structure according to claim 1, characterized in that, The pipe clamp, connecting bolts, limit bolts and temperature measuring blocks are all made of low-temperature resistant alloy steel.

5. The ultra-low temperature pipeline surface temperature measurement device using a pipe hoop structure according to claim 1, characterized in that, An opening is arranged at one end of the cavity in the temperature measuring block corresponding to the axial direction of the cryogenic pipeline.

6. The ultra-low temperature pipeline surface temperature measurement device using a pipe hoop structure according to claim 1 or 3, characterized in that, The temperature measuring element is a thermocouple or a diode.

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