Vacuum composite insulation prefabricated pipe test system and method

Abstract

The invention discloses a vacuum composite insulation prefabricated pipe test system and method. The system comprises a steam generation module, a test pipeline module, a condensation recovery module and a sensing monitoring module. The method comprises the following steps: a steam generation module provides low-pressure, medium-pressure and high-pressure temperature-adjustable steam through a graded heating unit, the steam is introduced into a test pipeline, pressure and temperature sensors are arranged at an inlet, the middle and an outlet of the test pipeline, and multi-dimensional parameter acquisition of pressure and temperature under different working conditions is realized; in the test process, the condensation recovery module recovers condensate water and a vapor-liquid mixture to the steam generator water tank, and energy recycling is achieved. The sensing monitoring module monitors the pressure and temperature of a vacuum layer and the state of a working pipe in real time. According to the method, key parameters such as the vacuum leak rate, the thermal resistance and the thermal loss are synchronously measured through the steps of preheating, stepped temperature rise, steady state testing and the like, the actual working condition can be accurately simulated, multi-parameter synchronous measurement is achieved, the testing efficiency and accuracy are improved, energy recycling is achieved, and a safe and stable operation guarantee mechanism is achieved.

Description

Technical Field

[0001] This invention relates to the field of performance testing technology for insulated pipes, specifically to a testing system and method for vacuum composite insulated prefabricated pipes. Technical Background Vacuum composite insulated precast pipes are widely used in heat transmission, industrial pipelines, and other fields due to their excellent thermal insulation performance. Their insulation effect mainly depends on the sealing performance of the vacuum layer, the properties of the insulation layer materials, and the overall structural design. Therefore, accurately testing key parameters such as vacuum leakage rate, thermal resistance, and heat loss is of great significance for pipeline design optimization, quality control, and engineering applications.

[0002] Existing testing technologies have several shortcomings: First, the testing systems struggle to simulate the high-temperature and high-pressure conditions of actual pipeline operation, leading to significant discrepancies between test data and actual performance. Second, the sensor deployment is insufficient, failing to accurately capture pressure and temperature changes at different locations within the pipeline, affecting the accuracy of thermal resistance and heat loss calculations. Third, vacuum leakage rate measurement and thermal performance testing are often independent, making simultaneous acquisition of multiple parameters difficult and resulting in low testing efficiency. Fourth, the direct discharge of condensate generated during testing leads to energy waste. Therefore, this invention proposes an integrated vacuum composite insulated prefabricated pipe testing system and method that can simulate actual temperature and pressure conditions, enabling simultaneous and accurate measurement of parameters such as vacuum leakage rate, thermal resistance, and heat loss, while simultaneously achieving energy recovery and utilization, thus overcoming the shortcomings of existing technologies. Summary of the Invention

[0003] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0004] The purpose of this invention is to provide a vacuum composite insulation prefabricated pipe testing system and method to solve the problems of inaccurate working condition simulation, incomplete parameter measurement, low testing efficiency and energy waste in existing testing technologies.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A vacuum composite insulated prefabricated pipe testing system includes a steam generation module, a test pipeline module, a condensate recovery module, and a sensing and monitoring module.

[0006] The steam generation module is used to provide steam at different temperatures and flow rates. It includes a water tank, a high-pressure water pump, and a steam generator connected in sequence. The steam generator is equipped with a primary heating unit and a secondary heating unit. Through staged heating, it can achieve precise control of steam from 200℃ to 550℃ to meet the testing requirements of different temperature steps.

[0007] The test pipeline module is the core of the test. From the outside in, the test pipeline consists of an outer protective pipe, a vacuum layer, an insulation layer, and a working pipe, which can realistically simulate the structure of a vacuum composite insulated prefabricated pipe in actual use. To comprehensively capture changes in pipeline parameters, pressure sensors and temperature sensors are installed at the inlet, middle, and outlet of the test pipeline. On each sensor layout interface, pressure sensors are installed horizontally inside the outer protective pipe and inside the working pipe, while temperature sensors are installed at the top, bottom, and horizontally of the outer protective pipe, ensuring multi-dimensional and multi-location parameter acquisition.

[0008] The condensate recovery module is used to process the condensate generated by the steam trap and the gas-liquid mixture cooled by the test pipeline, thereby achieving energy recovery. It includes a condenser and a circulating water pump. The gas-liquid mixture from the test pipeline outlet enters the condenser, is condensed by cold water to form condensate, and is then pumped by the circulating water pump to the water tank of the steam generator to preheat the water in the tank, improving energy utilization.

[0009] The sensing and monitoring module includes a pressure sensor and a temperature sensor. The pressure sensor is located in the vacuum layer and working layer of the test pipeline, respectively. It can collect the pressure values ​​of the three outer protective pipes along the axis and calculate the average value to provide accurate data for vacuum leakage rate calculation. Temperature sensors are arranged at the inlet, middle and outlet sections of the test pipeline. Each section has one temperature sensor at the top, bottom and side, which can collect the axial temperature of the pipeline at multiple angles under different temperatures, providing accurate data for calculating the thermal resistance and heat flow of the pipeline.

[0010] Drainage valves are installed on the test pipeline before the inlet and after the outlet to drain condensate in a timely manner. Drainage structures are installed before the inlet and at the lowest point of the test pipeline to drain condensate and air from the pipeline before the test, ensuring steam dryness and improving test accuracy.

[0011] A testing method for vacuum composite insulated precast pipes, using the above-mentioned system, includes the following steps: Preparation before the test: Check the experimental pipeline, valves, steam traps and the status of all instruments to confirm that there are no leaks, damages or other abnormalities, and that the steam traps are working properly; open the drainage structure at the lowest point of the pipeline and before the inlet to completely drain the condensate and air in the pipeline to ensure the dryness of the subsequent steam; record the initial ambient temperature, ambient humidity and atmospheric pressure to provide a reference for subsequent data correction.

[0012] Preheating Phase: The high-pressure water pump and heating unit of the steam generation module are started to introduce steam at the initial temperature into the test pipeline for preheating. During this process, the temperature of the thermocouples on the outer wall of the pipeline is monitored in real time. When the temperature approaches the initial temperature, the pipeline is kept stable for a period of time to ensure uniform temperature distribution. Simultaneously, the initial pressure of the vacuum layer is recorded by the sensor monitoring module. , The average value obtained from the measurements of the three axial outer tube pressure sensors is used as the benchmark value for subsequent leak rate calculation. Closely observe the pressure and temperature gauges on both sides of the test pipeline. If any abnormality is found, check the system and, if necessary, open the safety valve through the control module to release pressure.

[0013] Step-by-step temperature increase test: After preheating, the steam temperature is gradually increased at fixed temperature intervals through the staged heating unit of the steam generator; after each temperature step, the temperature is maintained at a stable level for a period of time to ensure the stability of the pipeline; during this process, the pressure and temperature gauges at both ends of the test pipeline are continuously observed to ensure they are functioning correctly, and the vacuum pressure value at the corresponding temperature is recorded. If the system experiences abnormal pressure or excessive temperature fluctuations, stop heating immediately and troubleshoot the problem. If necessary, open the safety valve to release pressure.

[0014] High-temperature steady-state test: As the temperature of the test pipe wall gradually approaches the target temperature, the steam generator is adjusted via the control module to stabilize the inlet flow velocity of the test pipe at a certain velocity, maintaining stable pipe operation; under this steady-state condition, the inlet temperature of the test pipe is recorded. (Average value taken from three cross-sectional measuring points) Inlet pressure outlet temperature (Average value taken from three cross-sectional measuring points), outlet pressure Simultaneously record the vacuum layer pressure at this time. (Obtained by averaging the pressure from three outer sheath pressure sensors along the axis), used for subsequent analysis of thermal insulation performance and heat loss.

[0015] After the high-temperature steady-state data acquisition is completed, the steam temperature is gradually reduced and the steam in the pipeline is vented. After the pressure drops to a safe range, the insulation structure of the joint section is removed, and the cross-sectional photos of the structure are taken for archiving and subsequent analysis.

[0016] Furthermore, the method equation for the vacuum composite insulation prefabricated pipe testing system is as follows: in, : Vacuum leakage rate, Pa·m³ / s; V: Effective volume of the vacuum chamber ; , Vacuum pressure values, Pa (absolute pressure), measured at the initial and final times. , : The time point corresponding to the pressure, in seconds (S).

[0017] in, : Outer radius of this layer, in meters; : The inner radius of this layer, in meters; The thermal conductivity of this layer material is W / m·K. Total thermal resistance of cylindrical layered structure (per unit length), K·m / W.

[0018] in, : Temperature of the outer surface of the steel pipe, K; : Temperature of the outer surface of the outer sheath, K; Heat flow per unit length, W / m.

[0019] in, Outer radius of the outer protective tube, in meters; Heat flux density per unit length of outer sheath, W / .

[0020] The beneficial effects of this invention are as follows: Through staged heating and flow rate control of the steam generator, the actual operating conditions of a temperature range of 200℃-550℃ and a flow rate of 0.2m / s can be accurately simulated, and the test data is closer to the actual performance.

[0021] Sensors are deployed in multiple locations and dimensions to simultaneously collect parameters such as vacuum layer pressure, pipeline inlet and outlet temperature and pressure, and temperature and pressure at different cross sections, providing complete data support for the calculation of multiple parameters such as vacuum leakage rate, thermal resistance, and heat loss.

[0022] The integrated system realizes a unified process from preheating, temperature rise, steady-state testing to data processing, and simultaneously measures vacuum leak rate and thermal performance parameters, which greatly improves testing efficiency.

[0023] The condensate recovery module recovers condensate to the steam generator water tank, achieving preheating circulation, reducing energy waste, and meeting energy-saving requirements.

[0024] It is equipped with a condensate drain valve, a safety valve, and a pressure monitoring mechanism, which can promptly drain condensate and release abnormal pressure to ensure a safe and stable testing process. Attached Figure Description

[0025] Figure 1 is a flowchart of a vacuum composite thermal insulation prefabricated pipe testing system according to the present invention; Figure 2 This is a schematic diagram of the cross-section of the vacuum composite insulation prefabricated pipe in this invention; Figure 3 This is a schematic diagram of the vacuum composite insulation prefabricated pipe cross-section measurement sensor in this invention; Figure 4 This is a schematic diagram showing the distribution of the horizontal temperature sensor and pressure sensor in the vacuum composite insulation prefabricated pipe of the present invention. Detailed Implementation

[0026] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] like Figure 1 As shown, this embodiment discloses a vacuum composite insulated precast pipe testing system, including a water tank 1, a high-pressure water pump 2, a steam generator 3, a primary heating unit 4, a secondary heating unit 5, a drain valve 6 at the inlet of the test pipe 8, a diameter reducer 7 at the inlet of the test pipe 8, pressure sensors 10 and temperature sensors 9 respectively arranged at the inlet section, middle section and outlet section of the test pipe 8, a diameter reducer 11 at the outlet of the test pipe 8, a drain valve 12 at the outlet of the test pipe 8, a condenser 13, and a circulating water pump 14.

[0028] like Figure 1 As shown, the steam flow process of this invention is as follows: the steam generator 3 is connected to the water tank 1 via the high-pressure water pump 2. The generated steam is transported to the test pipe 8 via the steam trap 6 and the reducer 7. The test pipe 8 is equipped with steam trap 6 and steam trap 12 at the inlet and outlet. The cooled steam enters the condenser 13 at the outlet of the test pipe 8 via the reducer 11 and steam trap 12. The condenser 11 receives the condensate from the steam trap 6 and the vapor-liquid mixture discharged from the test pipe 8. The condensate is returned to the water tank 1 via the circulating water pump 14. The inlet section, middle section and outlet section of the test pipe 8 are respectively equipped with a pressure sensor 10 and a temperature sensor 9.

[0029] like Figure 1 As shown, the test system of the present invention is equipped with steam traps 6 and 12 at the inlet and outlet of the test pipeline 8. The condensate generated by the steam traps 6 and 12, as well as the vapor-liquid mixture cooled by the test pipeline 8, all enter the condenser 13 for condensation. Cold water is introduced into one end of the condenser 13.

[0030] like Figure 1 As shown, the vapor-liquid mixture flowing out of the test pipe 8 still has a high temperature. After initial condensation in the condenser 13, the condensate in the condenser 13 is transported to the water tank 1 of the steam generator 3 by the power provided by the circulating water pump 14, thus preheating the water in the water tank 1 of the steam generator 3.

[0031] like Figure 2 As shown, the structure of the test pipe 8, from the outside to the inside, consists of an outer protective pipe 15, a vacuum layer 16, an insulation layer 17, and a working pipe 18.

[0032] like Figure 3As shown, on each cross-sectional surface where a sensor is located, a pressure sensor is installed in the horizontal direction inside the outer protective tube and inside the working tube; and a temperature sensor is installed at the top, bottom and horizontal direction of the outer protective tube.

[0033] During implementation, the first step is to perform an overall system status check: Confirm that all connections, valves, steam traps, and monitoring instruments in the experimental pipeline are in normal working order, with no leaks or damage, and ensure that the steam traps are working properly. Open the drainage structure located at the lowest point of the pipeline and before the inlet to completely drain the condensate and air accumulated in the pipeline, so as to ensure that the dryness of the subsequently introduced steam meets the test requirements. At the same time, record the ambient temperature, humidity and atmospheric pressure data at the beginning of the test.

[0034] Start the steam generation module to enter the preheating stage; This module uses a high-pressure water pump to deliver water to a steam generator, where it is gradually heated by primary and secondary heating units to produce high-temperature steam. Steam at 200℃ was introduced into the test pipeline module to preheat the entire pipeline evenly. During the preheating process, closely monitor the temperature of the outer wall of the pipeline. Once it stabilizes and approaches the preheating temperature of 200°C, maintain this state for a period of time and observe whether there are any abnormalities in the pressure and temperature gauges on both sides of the test pipeline. During this stage, data is collected by multiple pressure sensors placed at different positions along the axial direction of the vacuum layer, the average value is calculated, and recorded as the initial pressure value of the vacuum layer. This serves as a benchmark for subsequent evaluation of vacuum sealing performance; Monitor pipeline pressure and temperature throughout the process. If any abnormality is detected, immediately start the system for inspection. If necessary, release pressure through the safety valve to ensure operational safety.

[0035] After preheating, the system enters the stepped temperature rise test phase; The temperature of the input steam is gradually increased in 50°C increments through staged heating control of the steam generator. After reaching each new temperature threshold, the temperature is maintained at a stable level for a period of time to allow the internal state of the pipe to fully stabilize. During this process, pressure and temperature data at various measuring points in the pipeline are continuously observed and recorded, especially the vacuum pressure corresponding to the current temperature. ; Examine the response characteristics of the pipeline under different temperature conditions and the trend of vacuum pressure changes. If the system experiences abnormal pressure or exceeds the limit, immediately interrupt the heating process, troubleshoot the problem, and activate the safety valve device if necessary.

[0036] When the pipe wall temperature approaches 550℃, adjust the steam inlet flow rate to 0.2m / s to bring the system into the high-temperature steady-state test stage. Maintain stable operation under this condition, and simultaneously collect and record the inlet temperature of test pipeline 8. intermediate section temperature outlet temperature ( , and (Obtained by averaging the values ​​of three measuring points at various locations) Inlet pressure and export pressure ; Measure and record the current vacuum layer pressure. (Obtained by calculating the average value of three axial outer sheath pressure sensors), and the rate of change of vacuum layer pressure at this time is recorded simultaneously. The amount of condensate discharged from the steam trap is used to comprehensively analyze the insulation performance and heat loss of the pipeline.

[0037] After all steady-state tests are completed, the steam temperature is gradually reduced, and residual steam in the pipeline is vented. Once the system pressure returns to a safe level, the local insulation structure of the test pipe section can be disassembled, and the cross-sectional condition is photographed for subsequent structural analysis and archiving.

[0038] Vacuum leakage rate calculation for vacuum composite insulation prefabricated pipes: Where V: effective volume of the vacuum cavity, ; , Vacuum pressure values, Pa (absolute pressure), measured at the initial and final times. , : The time point corresponding to the pressure, in seconds (S).

[0039] Calculation of total thermal resistance per unit length of vacuum composite insulated precast cylindrical tube: in, : Outer radius of this layer, in meters; : The inner radius of this layer, in meters; The thermal conductivity of this layer material is W / m·K. .

[0040] Calculation of heat flow per unit length of vacuum composite insulated precast pipe: in, : Temperature of the outer surface of the steel pipe, K; : Temperature of the outer surface of the outer sheath, K.

[0041] Calculation of heat flux density per unit length of outer protective tube of vacuum composite insulation precast pipe: in, Outer radius of the outer protective tube, in meters (m).

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A testing system for vacuum composite insulated prefabricated pipes, characterized in that, The system includes a steam generation module, a test pipeline module, a condensate recovery module, and a sensor monitoring module. The steam generation module comprises a water tank, a high-pressure water pump, and a steam generator connected in sequence. The steam generator has a primary heating unit and a secondary heating unit. The test pipeline module includes a test pipeline, a reducer, and a drain valve. The test pipeline, from the outside in, consists of an outer protective pipe, a vacuum layer, an insulation layer, and a working pipe. Pressure sensors and temperature sensors are installed before the inlet, in the middle, and after the outlet of the test pipeline. On each sensor's cross-section, a pressure sensor is installed horizontally inside the outer protective pipe and the working pipe, and temperature sensors are installed at the top, bottom, and horizontally of the outer protective pipe. The condensate recovery module includes a condenser and a circulating water pump. The outlet of the test pipeline is connected to the condenser via a drain valve, and the condenser outlet is connected to the water tank of the steam generator via the circulating water pump. Drain valves are installed on both the inlet and outlet pipes of the test pipeline.

2. The vacuum composite insulation prefabricated pipe testing system according to claim 1, characterized in that, The steam generator can provide low-pressure, medium-pressure, and high-pressure steam, and supplies steam to the test pipeline in stages with a fixed temperature, increasing or decreasing the supply of steam step by step.

3. The vacuum composite insulation prefabricated pipe testing system according to claim 1, characterized in that, The test pipeline is equipped with a drainage structure at the inlet and the lowest point to drain condensate and air from the pipeline.

4. The vacuum composite insulation prefabricated pipe testing system according to claim 1, characterized in that, The condensation recovery module recovers the condensate generated by the steam trap at the inlet of the test pipeline, as well as the vapor-liquid mixture cooled by the test pipeline.

5. The vacuum composite insulation prefabricated pipe testing system according to claim 1, characterized in that, The sensing and monitoring module includes a vacuum measuring instrument, a temperature sensor, and a pressure sensor. The vacuum measuring instrument is connected to the vacuum layer of the test pipeline, and the temperature and pressure sensors collect pressure and temperature values ​​at three points along the axial direction of the outer protective pipe.

6. A testing method for vacuum composite insulated precast pipes, employing the system described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Check the experimental pipeline, valves, steam traps and instrument status. After confirming that there are no abnormalities, open the drainage structure at the lowest point of the pipeline and before the inlet to drain the condensate and air in the pipeline to ensure the dryness of the steam. Record the initial ambient temperature, humidity and atmospheric pressure. Step 2: Start the steam generation module and introduce initial medium-pressure steam into the test pipeline, allowing the pipeline temperature to gradually rise until the temperature measured by the outer wall temperature sensor approaches the initial temperature and remains stable. Simultaneously, record the initial pressure of the vacuum layer. , The values ​​were obtained by averaging the pressure readings from three outer sheath pressure sensors along the axial direction. Step 3: Gradually increase the steam temperature at fixed intervals, maintaining a stable temperature after each temperature increment. Observe the pressure at both ends of the test pipe and the status of the thermometer, and record the corresponding vacuum pressure values. If the system malfunctions, stop heating and troubleshoot the problem. Step four: When the temperature of the experimental tube wall approaches the target temperature, stabilize the inlet flow rate at a suitable speed, maintain stable pipeline operation, and record the inlet temperature of the experimental tube. Import pressure outlet temperature Export pressure and vacuum layer pressure , The values ​​are obtained by averaging the pressure values ​​of the three outer sheath pressure sensors along the axis.

7. The vacuum composite insulation prefabricated pipe testing system according to claim 1, characterized in that, The formula for calculating the vacuum leakage rate of the vacuum composite insulation prefabricated pipe is as follows: in, : Vacuum leakage rate, Pa·m³ / s; V: Effective volume of the vacuum chamber ; , Vacuum pressure values, Pa (absolute pressure), measured at the initial and final times. , : The time point corresponding to the pressure, in seconds (S).

8. The vacuum composite insulation prefabricated pipe testing system according to claim 1, characterized in that, The formula for calculating the unit length thermal resistance of the vacuum composite insulated precast cylindrical tube is as follows: in, : Outer radius of this layer, in meters; : The inner radius of this layer, in meters; The thermal conductivity of this layer material is W / m·K. Total thermal resistance of cylindrical layered structure (per unit length), K·m / W.

9. The vacuum composite insulation prefabricated pipe testing system according to claim 1, characterized in that, The formula for calculating the heat flow per unit length of the vacuum composite insulated prefabricated pipe is as follows: in, : Temperature of the outer surface of the steel pipe, K; : Temperature of the outer surface of the outer sheath, K; Heat flow per unit length, W / m.

10. The vacuum composite insulation prefabricated pipe testing system according to claim 1, characterized in that, The formula for calculating the heat flux density per unit length of the outer protective tube of the vacuum composite insulation precast pipe is as follows: in, Outer radius of the outer protective tube, in meters; Heat flux density per unit length of outer sheath, W / .

11. The method according to claim 6, characterized in that, In steps two and three, if the system pressure is abnormal, open the safety valve to release the pressure.

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