A thermocouple temperature measuring device for high temperature and high pressure pipelines

Abstract

The application provides a high-temperature and high-pressure pipeline thermocouple temperature measuring device, and belongs to the technical field of engineering fluid thermal power and hydraulic technology, and comprises a thermocouple seat and a fixed base, the thermocouple seat is fixed in the fixed base, the fixed base and the bottom of the thermocouple are installed on the surface of a measuring pipeline, the thermocouple is fixed on the thermocouple seat, the thermocouple enters the inside of the measuring pipeline through a thermocouple guide pipe, and the thermocouple transmits real-time temperature data at a measuring position to an external data acquisition system through a thermocouple probe. The application utilizes the lengthened thermocouple base to reduce the influence of high temperature at the bottom on thermal expansion and contraction of the sealed end of the top of the thermocouple seat, reduces air leakage under high pressure, and is convenient for replacement and maintenance. Meanwhile, the inside is provided with a guide pipe, the lengthened thermocouple enters the measuring pipeline through the guide pipe, the guide pipe plays a guiding and fixing role on the thermocouple, reduces the bending of the thermocouple caused by high flow, and reduces the error phenomenon in measurement.

Description

Technical Field

[0001] This invention belongs to the field of engineering fluid thermal hydraulic technology, specifically relating to a thermocouple temperature measurement device for high-temperature and high-pressure pipelines. Background Technology

[0002] Fourth-generation small modular reactors (SMRs) are characterized by their compact size and high efficiency, and are widely used in space reactors and small reactors. In SMRs, coolants typically include lead-bismuth, helium, helium-xenon, and supercritical carbon dioxide. Unlike the Rankine cycle used in pressurized water reactors, SMRs employ a direct Brayton cycle to improve cycle performance; throughout the cycle, the coolant needs to be maintained at high temperature and high pressure.

[0003] Currently, research on fourth-generation small modular reactors (SMRs) is still in the exploratory stage, requiring substantial experimental data. However, the thermal expansion and contraction of materials under high temperature and pressure conditions, leading to damage and leaks in valves, flanges, and thermocouples, makes it difficult to easily obtain experimental data on the fluid within pipelines under these conditions. Therefore, accurately measuring the fluid temperature within high-temperature and high-pressure devices can support research on the heat transfer characteristics of different coolants and lay the foundation for the research of fourth-generation SMRs. Summary of the Invention

[0004] The purpose of this invention is to provide a thermocouple temperature measuring device for high-temperature and high-pressure pipelines to solve the problems mentioned in the background art.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A thermocouple temperature measuring device for a high-temperature and high-pressure pipeline includes: a thermocouple holder and a fixed base. The thermocouple holder is fixed inside the fixed base. The fixed base and the bottom of the thermocouple are installed on the surface of the measuring pipeline. The thermocouple is fixed on the thermocouple holder. The thermocouple enters the interior of the measuring pipeline through a thermocouple guide tube. The thermocouple transmits real-time temperature data at the measuring location to an external data acquisition system through a thermocouple probe.

[0007] Furthermore, the thermocouple holder and the fixed base are integrally and vertically installed on the measuring pipe.

[0008] Furthermore, the thermocouple passes through a thermocouple guide tube, and the outer wall of the thermocouple guide tube is connected to the inner wall of the hollow cylinder of the thermocouple holder through a guide tube fixing member.

[0009] Furthermore, the top of the thermocouple holder is connected to a sealing sleeve via a fastening nut, and the sealing sleeve secures the thermocouple.

[0010] Furthermore, the lower part of the thermocouple guide tube enters the measurement position through an opening on the surface of the measuring pipe.

[0011] Furthermore, the length of the thermocouple holder is not less than 10cm.

[0012] Furthermore, when the outer diameter of the thermocouple holder is less than 10 mm, the height H of the thermocouple holder is greater than 15 cm.

[0013] Furthermore, the hollow cylinder of the thermocouple holder has a wall thickness of 1~2mm.

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

[0015] This invention avoids damage to the sealing point of the thermocouple holder at the top of the thermocouple holder and leakage caused by thermal expansion and contraction due to the high temperature and pressure of the heating pipe. Simultaneously, the addition of an internal thermocouple guide tube to secure the extended thermocouple enables precise measurement of temperature data at a specified location. The extended design also facilitates secondary replacement and maintenance of the thermocouple. This invention provides support for research on the heat transfer characteristics of different coolants and lays the foundation for research on fourth-generation small modular reactors. Attached Figure Description

[0016] Appendix Figure 1 This is a schematic diagram of the structure of the present invention;

[0017] Appendix Figure 2 This is a cross-sectional view of the present invention;

[0018] Appendix Figure 3 It is attached Figure 1 Top view;

[0019] Appendix Figure 4 It is attached Figure 1 A bottom view;

[0020] Appendix Figure 5 This is a schematic diagram of the temperature distribution along the height direction calculated by numerical simulation in this invention;

[0021] Appendix Figure 6 This is a temperature change curve of the top temperature under different aspect ratios, calculated by numerical simulation according to the present invention.

[0022] In the attached diagram: 1. Measuring pipe; 2. Fixed base; 3. Thermocouple holder; 4. Fastening nut; 5. Thermocouple; 6. Sealing sleeve; 7. Top thread of the thermocouple holder; 8. Thermocouple guide tube; 9. Guide tube fixing component; 10. Temperature distribution of a 15cm long thermocouple holder; 11. Temperature distribution of a 10cm long thermocouple holder. Detailed Implementation

[0023] The present invention will now be further described with reference to the accompanying drawings.

[0024] This invention provides a thermocouple temperature measuring device for high-temperature and high-pressure pipelines, such as... Figure 1-4 As shown, it includes: thermocouple holder 3, fastening nut 4, thermocouple guide tube 8, sealing sleeve 6, fixing base 2, and guide tube fixing component 9; the fixing base 2 is integrated with the bottom of the thermocouple 5, and the fixing base 2 is welded to the surface of the measuring pipe 1. The thermocouple 3 is fixed on the thermocouple holder 3 and enters the interior of the measuring pipe 1 through the thermocouple guide tube 8. The real-time temperature data at the measurement position is transmitted to the external data acquisition system through the thermocouple probe.

[0025] In this embodiment, an extended thermocouple device is vertically installed on the surface of the measuring pipe. The thermocouple base and the fixed base are integrally connected. The fixed base is connected to the surface of the measuring pipe by welding, and the top is connected to the fastening nut by threads.

[0026] As attached Figure 1-2 As shown, the thermocouple holder 3 has a thermocouple guide tube 8 inside, which is connected to the outer wall of the thermocouple guide tube and the inner wall of the thermocouple holder through the guide tube fixing member 9. The guide tube fixing member 9 is set at a certain distance, with a thickness of 1mm, and is in the shape of a ring. The inner ring is connected to the outer wall of the thermocouple guide tube, and the outer ring is connected to the inner wall of the thermocouple holder. The top of the thermocouple guide tube 8 is connected to the center of the top cover of the thermocouple holder 3, and the bottom extends out of the bottom of the thermocouple holder 3 and into the measuring pipe.

[0027] This invention utilizes an elongated thermocouple base to reduce the impact of high temperatures at the bottom on the thermal expansion and contraction of the sealing end at the top of the thermocouple base, thereby reducing leakage under high pressure and facilitating replacement and maintenance. Simultaneously, an internal guide tube is incorporated, through which the elongated thermocouple enters the measuring pipeline. The guide tube guides and fixes the thermocouple, reducing the risk of thermocouple bending and measurement errors caused by high flow rates. Through the coordinated design of the elongated thermocouple base and the guide tube, accurate measurement of the fluid temperature inside high-temperature, high-pressure pipelines is achieved, providing support for research on the heat transfer characteristics of different coolants and laying the foundation for research on fourth-generation small modular reactors.

[0028] As attached Figure 3-4 As shown, the thermocouple holder 3 has a circular hole at its center smaller than the diameter of the sealing sleeve. The thermocouple passes through the nut, then through the sealing sleeve into the thermocouple base via a thermocouple guide tube. The thermocouple probe extends from the small hole at the bottom to measure the temperature at the measuring point. The locking nut 4 is connected to the thermocouple holder 3 by threads. By continuously applying force, the sealing sleeve fixes the position of the thermocouple and achieves a good sealing effect.

[0029] The basic principle of this invention is a steady-state one-dimensional fin heat conduction model, whose heat conduction differential equation can be simplified as follows:

[0030] ,

[0031] In the formula, h is the convective heat transfer coefficient; P is the perimeter of the heat transfer cross section; t is the temperature variable; A c It is the cross-sectional area.

[0032] The surface of the thermocouple holder experiences heat transfer via natural convection of air, as expressed below:

[0033]

[0034] In the formula, C and n are coefficients determined by Gr; Nu is the Nusselt number; L is the characteristic length; λ is the thermal conductivity of air; Gr is the Grashof number; Pr is the Prandtl number; λ, Gr, and Pr are all calculated based on the arithmetic mean temperature of the wall and the air. For an accurate wall temperature, a value of h can be assumed first, the wall temperature can be calculated, and the process can be iterated until convergence.

[0035] The temperature distribution in the thermocouple holder can be expressed as:

[0036]

[0037] In the formula, T ∞ The ambient temperature is represented by T0; the surface temperature of the measuring pipe is represented by T0; x is the position along the height of the thermocouple holder; and H is the height of the thermocouple holder. .

[0038] Taking the dimensions of this embodiment as an example, calculate the lengthening ratio of the stainless steel thermocouple holder; the inner diameter of the thermocouple holder is 5mm and the outer diameter is 7mm; the surface temperature of the heating pipe is 800℃ and the ambient temperature is 30℃.

[0039] In this embodiment, in the convective heat transfer calculation, C=0.59, n=0.25; the iterative calculation yields a top temperature of 134℃ at a height of 10cm. This is a theoretical calculation; in actual practice, h is underestimated, and this calculation neglects high-temperature radiative heat dissipation.

[0040] Therefore, numerical calculation models were established for heights of 10cm and 15cm, with a hot end temperature of 800℃ and a wall surface temperature of h = 13 W / (m²). 2 Calculate solid-state heat conduction under boundary conditions of ⋅K and ambient temperature of 30℃.

[0041] like Figure 5 As shown, the temperature distribution is obtained from numerical solutions. In a cylinder 10cm high, the average temperature drop per centimeter is 69.7℃; in a cylinder 15cm high, the temperature drop per centimeter is 50.3℃; the top temperature drops from 103℃ at 10cm to 45.8℃ at 15cm.

[0042] Based on theoretical calculations, with h = 13 W / (m 2 ⋅K) Simplified calculation: Calculate the length-to-diameter ratio required to cool the top of a hollow cylinder with a wall thickness of 1mm and an outer diameter of 5mm, 7mm, 10mm, and 15mm to below 100℃. The larger the outer diameter, the smaller the required length-to-diameter ratio. For a diameter of 5mm, the required length-to-diameter ratio r > 18.

[0043] like Figure 6 The figure shows the numerical calculation results, with h = 13 W / (m 2 (K) Simplified calculations: Calculate the temperature change at the top with different length-to-diameter ratios for a wall thickness of 1mm and outer diameters of 5mm, 7mm, 10mm, and 15mm. Aiming to cool the top to below 100℃, the smaller the outer diameter, the larger the required length-to-diameter ratio. With a 5mm outer diameter, the required length-to-diameter ratio r>19 is needed to cool the top to below 100℃, which is close to the theoretical calculation. The required length-to-diameter ratio varies for different pipe diameters, but shows a consistent trend in height; that is, when the temperature at the top drops below 100℃, the height of the thermocouple holder is greater than 10cm. The larger the pipe diameter, the higher the required height. Because thermocouple holders are often combined with circular pipes, the outer diameter of the pipe should not be too large. When the outer diameter is less than 10mm, a thermocouple holder with a height greater than 10cm is sufficient to meet the cooling requirements. To ensure the top is sealed, the temperature needs to be controlled below 100℃; the design of the thermocouple holder should meet the design requirements of an outer diameter less than 10mm and a thermocouple holder height H>15cm.

[0044] This example uses stainless steel, which allows for the use of materials with lower thermal conductivity to increase thermal resistance and further reduce the top temperature.

[0045] By extending the thermocouple mount, the top can be cooled, improving the element's temperature and pressure resistance, and enabling temperature measurement inside the experimental pipe at higher temperatures and pressures.

[0046] By fixing the guide tube, it can withstand the impact of high flow rates of various coolants, enabling accurate temperature measurement inside high-temperature, high-pressure, and high-flow-rate pipelines.

[0047] To ensure top sealing, the temperature must be controlled below 100℃; the design of the thermocouple holder should meet the requirements of an outer diameter of less than 10mm and a height H of more than 15cm.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A thermocouple temperature measuring device for high-temperature and high-pressure pipelines, characterized in that, include: Thermocouple holder (3) and fixed base (2) are provided. Thermocouple holder (3) is fixed inside fixed base (2). Fixed base (2) and bottom of thermocouple (3) are installed on the surface of measuring pipe (1). Thermocouple (5) is fixed on thermocouple holder (3). Thermocouple (5) enters the measuring pipe (1) through thermocouple guide tube (8). Thermocouple (5) transmits real-time temperature data at the measurement position to external data acquisition system through thermocouple probe.

2. The thermocouple temperature measuring device for high-temperature and high-pressure pipelines according to claim 1, characterized in that, The thermocouple holder (3) and the fixed base (2) are installed vertically on the measuring pipe (1) as a whole.

3. The thermocouple temperature measuring device for high-temperature and high-pressure pipelines according to claim 1, characterized in that, The thermocouple (5) passes through the thermocouple guide tube (8), and the outer wall of the thermocouple guide tube (8) is connected to the inner wall of the hollow cylinder of the thermocouple seat (3) through the guide tube fixing member (9).

4. The thermocouple temperature measuring device for high-temperature and high-pressure pipelines according to claim 1 or 3, characterized in that, The top of the thermocouple holder (3) is connected to the sealing sleeve (6) by a fastening nut (4), and the sealing sleeve (6) fixes the thermocouple (5).

5. The thermocouple temperature measuring device for high-temperature and high-pressure pipelines according to claim 4, characterized in that, The lower part of the thermocouple guide tube (8) enters the measurement position through an opening on the surface of the measuring pipe (1).

6. The thermocouple temperature measuring device for high-temperature and high-pressure pipelines according to claim 1, characterized in that, The length of the thermocouple mount shall not be less than 10cm.

7. The thermocouple temperature measuring device for high-temperature and high-pressure pipelines according to claim 1, characterized in that, When the outer diameter of the thermocouple holder (3) is less than 10 mm, the height H of the thermocouple holder (3) is greater than 15 cm.

8. The thermocouple temperature measuring device for high-temperature and high-pressure pipelines according to claim 1, characterized in that, The hollow cylinder of the thermocouple holder (3) has a wall thickness of 1~2mm.

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