Medium pressure small temperature difference evaporation test loop device

Abstract

The present application belongs to the technical field of nuclear energy heating equipment test, and particularly relates to a medium-pressure small-temperature-difference evaporation test loop device, comprising: a hot-side tube loop, the hot-side tube loop being an open loop, and the hot-side tube loop performing heat exchange with a hot-side tube loop of a test prototype; and a cold-side shell loop, the cold-side shell loop being a closed loop, and the cold-side shell loop performing heat exchange with a cold-side shell loop of the test prototype. The present application adopts an independent double-circulation structure design of a cold-side closed loop and a hot-side open loop, realizes independent regulation and control of a hot-side heat source output and a cold-side evaporation process, and avoids the problem of mutual interference of the cold side and the hot side, so that the cold side and the hot side can be accurately matched in pressure and temperature parameters, and the problem of poor working condition adaptability of the existing loop is solved.

Description

Technical Field

[0001] This invention belongs to the field of nuclear energy heating equipment testing technology, specifically relating to a medium-pressure small temperature difference evaporation test circuit device. Background Technology

[0002] The Xuwei Nuclear Heating Project, the world's first innovative project to couple nuclear energy with the petrochemical industry on a large scale and to operate a pressurized water reactor (PWR) and a high-temperature gas-cooled reactor (HTGR), utilizes the Hualong One third-generation nuclear power technology combined with a fourth-generation HTGR to provide large-scale industrial steam for the petrochemical industrial base. The Hualong One evaporator is the core and critical equipment of the steam conversion system. This evaporator employs small temperature difference evaporation technology, with a design temperature difference of approximately 10°C between the inside and outside of the tubes. Considering the thermal resistance of fouling, the superheat on the outer wall of the heat exchange tubes is ≤4°C. The heat transfer characteristics and operational stability of this type of small temperature difference evaporator directly determine the steam output capacity of the nuclear heating system.

[0003] Existing evaporator test loop devices are mostly designed for conventional temperature difference evaporation conditions, and there are two main implementation schemes: one is the low-temperature multi-effect evaporation test loop, which is suitable for atmospheric pressure, low temperature and small temperature difference scenarios. It adopts an open circulation structure, with low pressure and temperature control accuracy, and cannot reproduce the operating parameters of nuclear heating evaporators at medium pressure (5.0~6.5MPa) and medium temperature (250~280℃); the other is the conventional medium-pressure evaporator test loop, which adopts a single closed circulation structure and has no dedicated pressure stabilization and liquid level compensation components. Under small temperature difference conditions, it is prone to pressure fluctuations and liquid level imbalances, resulting in unstable control of wall superheat during the test and large deviations between test data and actual operating data.

[0004] In summary, the existing evaporator test loop device has the following defects:

[0005] 1. Poor adaptability to operating conditions: The existing test circuit cannot stably reproduce the core parameters of medium-pressure, small-temperature-difference evaporation. The pressure and temperature control accuracy is low and the fluctuation range is large, which cannot meet the test requirements.

[0006] 2. Unreasonable design of the circulation structure: The low-temperature multi-effect evaporation test circuit is an open structure without a pressure stabilizing component, which is prone to medium leakage under medium pressure conditions; the conventional medium pressure test circuit has a cold and hot side circulation structure, which has large interference on the cold and hot sides and cannot accurately control the output of the heat source on the hot side and the evaporation process on the cold side.

[0007] 3. Lack of dedicated pressure stabilization and liquid level compensation mechanism: Small temperature difference evaporation is highly sensitive to changes in liquid level and pressure. The existing circuit lacks a targeted liquid level compensation and nitrogen pressure stabilization structure. Liquid level fluctuations and pressure changes are likely to occur during the test, causing the wall superheat to deviate from the target value and the test data to be distorted.

[0008] 4. Insufficient accuracy of experimental data acquisition: The temperature and pressure measuring instruments of the existing circuit are not compatible with the small temperature difference operating conditions, resulting in large measurement errors and making it impossible to accurately obtain heat transfer characteristic data under small temperature differences;

[0009] 5. Integrated design of flow regime observation and control: The existing loop does not have a visual observation window, so it is impossible to monitor the flow regime changes in the evaporation process in real time, and it is difficult to verify the flow regime stability under small temperature difference conditions.

[0010] Meanwhile, the existing test loop uses a general tube bundle structure for heat exchange simulation on the hot and cold sides, without matching the tube bundle parameters of the Hualong One medium-pressure evaporator. It cannot accurately simulate the pool boiling + natural convection synergistic heat transfer process under small temperature difference, and lacks a dedicated flow state observation and accurate data acquisition module, making it difficult to meet the test verification needs of medium-pressure small temperature difference evaporation technology.

[0011] It is evident that at present, there are no engineering application cases of small temperature difference evaporation technology under medium pressure conditions, both domestically and internationally, and there is a significant technological gap in related experimental verification equipment. Summary of the Invention

[0012] The present invention addresses the above-mentioned technical problems by providing a medium-pressure, small-temperature-difference evaporation test circuit device.

[0013] A medium-pressure, small-temperature-difference evaporation test circuit device, the medium-pressure, small-temperature-difference evaporation test circuit device comprising:

[0014] The hot-side tube-side loop is an open loop, and the hot-side tube-side loop exchanges heat with the hot-side tube-side of the test prototype.

[0015] The cold-side shell-side loop is a closed loop, and the cold-side shell-side loop exchanges heat with the cold-side shell-side of the test prototype.

[0016] Optionally, the hot-side tube circuit includes:

[0017] A steam generator is used to generate saturated steam. The outlet of the steam generator is connected in sequence via pipeline to a first shut-off valve, a first regulating valve, a steam pipeline heater, a steam vortex flow meter, and the hot-side tube inlet of the test prototype.

[0018] A condensate tank is provided, with its inlet connected via a pipeline to the hot-side outlet of the test prototype. The bottom outlet of the condensate tank is connected via a pipeline to an outlet pipeline balance flow meter, a second regulating valve, a third regulating valve, and a hot-side silencer.

[0019] Optionally, the steam generator is a hot-side steam generating unit, the steam generator is designed with a pressure of 9.0 MPa and a design temperature of 320°C.

[0020] Optionally, a first electric heating rod is arranged at the bottom of the steam generator to heat the medium inside the steam generator in order to generate saturated steam.

[0021] Optionally, the heating power of the first electric heating rod is 500 kW.

[0022] Optionally, the top of the steam generator is connected in sequence via pipeline to a first safety valve and a pressure relief regulating valve.

[0023] Optionally, the heating power of the steam pipeline heater is 15kW, and the steam pipeline heater is enveloped on the outer wall of the pipeline between the first regulating valve and the steam vortex flow meter.

[0024] Optionally, the steam pipe heater is used to heat saturated steam into slightly superheated steam, and the steam inlet temperature of the hot-side tube inlet of the test prototype is controlled between 270°C and 280°C by the steam pipe heater.

[0025] Optionally, the top of the condensate tank is connected to the hot-side tube inlet of the test prototype via a vapor balance pipeline.

[0026] Optionally, a level gauge is arranged on the hydrophobic tank for level monitoring.

[0027] Optionally, the hot-side tube circuit uses the first regulating valve, the second regulating valve, the third regulating valve, and the steam pressure in the steam generator to regulate the hot-side tube outlet back pressure of the test prototype.

[0028] Optionally, the hot-side pressure adjustment range is 5.0 MPa to 6.5 MPa.

[0029] Optionally, the hot-side tube circuit can regulate the hot-side steam flow rate of the hot-side tube circuit through the first regulating valve, the second regulating valve, and the third regulating valve.

[0030] Optionally, the hot-side flow rate control range is 0.25 t / h ~ 1.2 t / h.

[0031] Optionally, the cold-side shell-side circuit includes:

[0032] The main circulating pump is connected in sequence via pipeline to the main circuit pipeline regulating valve, the main circuit pipeline balance flow meter, the electric heater, the cold side shell-side inlet pipeline isolation valve, and the cold side shell-side inlet of the test prototype.

[0033] The mixer, the cold-side shell-side outlet of the prototype is connected in sequence to the cold-side shell-side outlet pipeline isolation valve, the fourth regulating valve and the steam inlet of the mixer via pipeline, and the outlet of the circulating main pump is also connected in sequence to the bypass branch pipeline Venturi flow meter, the bypass branch regulating valve and the subcooled water inlet of the mixer via pipeline.

[0034] The siphon tank is connected in sequence to the fourth shut-off valve and the inlet of the siphon tank via a pipeline, and the outlet of the siphon tank is connected in sequence to the fifth shut-off valve and the inlet of the circulating main pump via a pipeline.

[0035] Optionally, the circulating main pump is a vertical canned pump with variable frequency control design, and the cold side shell-side circuit achieves cold side flow control by adjusting the variable frequency of the circulating main pump and the opening degree of the main circuit pipeline regulating valve and the bypass branch regulating valve.

[0036] Optionally, the rated flow rate of the circulating main pump is 5 m³ / s. 3 / h and the head is 80m.

[0037] Optionally, the pipeline between the fifth shut-off valve and the inlet of the circulating main pump is an upstream pipeline of the circulating main pump inlet and is divided into two branches. One branch connects the fifth shut-off valve to the fifth regulating valve and the inlet Venturi flow meter in sequence via the pipeline. The other branch connects the fifth shut-off valve to the inlet pipeline balance flow meter, the sixth regulating valve, the main cooler, and the inlet Venturi flow meter in sequence via the pipeline. The inlet Venturi flow meter is connected to the inlet of the circulating main pump, so that the two branches converge into the inlet of the circulating main pump after passing through the inlet Venturi flow meter.

[0038] Optionally, the siphon tank is filled with nitrogen gas, which flows out through a nitrogen cylinder group. The nitrogen cylinder group is connected in sequence to a check valve, a seventh shut-off valve, and the top of the siphon tank via a nitrogen filling pipeline.

[0039] Optionally, an exhaust valve is connected to the nitrogen filling pipeline between the seventh shut-off valve and the siphon tank.

[0040] Optionally, a second electric heating rod is arranged at the bottom of the siphon tank to heat the medium inside the siphon tank.

[0041] Optionally, a second safety valve is connected to the top of the siphon tank.

[0042] Optionally, the outlet of the electric heater is connected in sequence via a pipeline to the second isolation valve and the fourth regulating valve; the medium-pressure small temperature difference evaporation test circuit device has a switching function for independent operation of the cold-side closed circuit and operation connected to the cold-side shell side of the test prototype.

[0043] The cold-side shell-side inlet pipeline isolation valve and the cold-side shell-side outlet pipeline isolation valve are closed to isolate the test prototype, and the subcooled water in the cold-side shell side of the test prototype is heat-exchanged through the hot-side pipeline loop.

[0044] The second isolation valve is opened, and the cold-side closed circuit is heated through the circulating main pump, the main circuit pipeline regulating valve, the bypass branch regulating valve and the electric heater. The cold-side closed circuit is also closed-loop operated through the circuit outlet pipeline connected to the siphon tank.

[0045] When the temperature difference and pressure difference between the cold-side closed loop and the cold-side shell side of the test prototype are within a preset range, the isolation valves of the cold-side shell side inlet pipeline and the cold-side shell side outlet pipeline are opened, and the second isolation valve is closed, thereby connecting the cold-side closed loop with the cold-side shell side of the test prototype.

[0046] Optionally, the cold-side shell-side circuit further includes:

[0047] A vapor-liquid separator, the inlet of which is connected via a pipeline to the cold-side shell-side outlet of the test prototype, and the outlet of which is connected via a pipeline in sequence to a heat exchanger, an outlet pipeline regulating valve, an outlet Venturi flow meter, a third shut-off valve, and a fourth shut-off valve.

[0048] Optionally, the heat exchanger is a microchannel heat exchanger.

[0049] Optionally, a drain and pressure relief pipeline is arranged at the bottom of the vapor-liquid separator, and the bottom of the vapor-liquid separator is sequentially connected to a second shut-off valve, a seventh regulating valve, and a cold-side silencer via the drain and pressure relief pipeline.

[0050] Optionally, each regulating valve in the medium-pressure small temperature difference evaporation test circuit device has a pipeline flow regulation function, each isolation valve in the medium-pressure small temperature difference evaporation test circuit device has a pipeline system isolation function, and each regulating valve and each isolation valve in the medium-pressure small temperature difference evaporation test circuit device is driven by an electric valve.

[0051] Optionally, the medium in the hot-side tube-side circuit and the medium in the cold-side shell-side circuit are both deionized water.

[0052] Optionally, all pipelines in the hot-side tube-side circuit and the cold-side shell-side circuit are made of stainless steel 304.

[0053] Optionally, the test prototype is equipped with a scaled-down tube bundle that matches the structure of a preset medium-pressure evaporator.

[0054] The cavity of the test prototype is equipped with several visualization observation windows, and the visualization observation windows are equipped with visualization observation devices.

[0055] The hot-side tube side and cold-side shell side of the test prototype are equipped with inlet and outlet pipelines, as well as the cavity of the test prototype, which are equipped with monitoring instruments for monitoring at least one of the parameters of temperature, pressure and liquid level. The monitoring instruments and the equipment control signals of the test prototype are all connected to the test loop acquisition system to realize real-time data acquisition, control and storage.

[0056] Optionally, the preset medium-pressure evaporator is a Hualong One medium-pressure evaporator.

[0057] Optionally, the visualization observation window is a quartz glass window.

[0058] Optionally, the outer wall surface of the heat transfer tubes of the test prototype is provided with a tube bundle wall surface temperature measuring instrument.

[0059] Optionally, the tube bundle wall temperature measuring instrument is an N-type thermocouple.

[0060] Optionally, the tube bundle wall temperature measuring instrument is an A-grade instrument with a calibration error of ±0.5℃ and a spacing of 1000mm between adjacent temperature measuring points.

[0061] Optionally, each region of the heat transfer tube bundle bend section and straight section section of the cold side shell side of the test prototype is provided with two cold side shell side visualization observation windows, one of which is a supplementary light source window and the other is a shooting window.

[0062] Optionally, the hot-side tube outlet box area of ​​the test prototype is provided with three hot-side tube visualization windows, one of which is a supplementary light source window, and the other two are shooting windows, which are symmetrically distributed on the front and rear sides of the hot-side tube outlet box of the test prototype.

[0063] Optionally, the monitoring instruments include at least one of the following: a hot-side temperature monitoring instrument for monitoring the inlet and outlet temperatures of the hot-side tubes of the test prototype; a hot-side pressure monitoring instrument for monitoring the inlet and outlet pressures of the hot-side tubes of the test prototype; a cold-side temperature monitoring instrument for monitoring the inlet and outlet temperatures of the cold-side shell of the test prototype; a cold-side pressure monitoring instrument for monitoring the inlet and outlet pressures of the cold-side shell of the test prototype; a vapor phase temperature monitoring instrument for monitoring the vapor phase temperature of the test prototype; a vapor phase pressure monitoring instrument for monitoring the vapor phase pressure of the test prototype; a liquid phase temperature monitoring instrument for monitoring the liquid phase temperature of the test prototype; a liquid phase pressure monitoring instrument for monitoring the liquid phase pressure of the test prototype; and a liquid level monitoring instrument for monitoring the liquid level of the test prototype.

[0064] Optionally, both the hot-side temperature monitoring instrument and the cold-side temperature monitoring instrument are platinum resistance thermometers with an accuracy of 1 / 3B class and a calibration error of ±0.1%.

[0065] Optionally, both the vapor phase temperature monitoring instrument and the liquid phase temperature monitoring instrument use type E thermocouples with an accuracy of Class A.

[0066] Optionally, each temperature monitoring point in the test prototype is equipped with two temperature monitoring instruments.

[0067] Optionally, the hot-side pressure monitoring instrument, the cold-side pressure monitoring instrument, the vapor phase pressure monitoring instrument, and the liquid phase pressure monitoring instrument all use RoseMount2088 pressure transmitters with an accuracy of ±0.1%.

[0068] Optionally, each pressure monitoring point in the test prototype used to monitor the vapor and liquid phase pressures of the equipment is equipped with two pressure monitoring instruments.

[0069] Optionally, there are two level monitoring instruments, namely a magnetic float level gauge and a differential pressure level gauge, which enable the test prototype to form a dual level measurement mode. The magnetic float level gauge is preferably 0~0.8m in range, and the differential pressure level gauge is preferably a RoseMount3051 pressure transmitter with an accuracy of ±0.1%.

[0070] Optionally, the visualization observation device includes a camera, a supplementary light source, a power supply, and an observation terminal. The camera's imaging surface faces the visualization observation window to capture the internal working conditions of the test prototype. The camera's signal output terminal is connected to the observation terminal. The supplementary light source is located on the side of the camera's imaging surface to provide a light source for the camera's imaging. The supplementary light source's power supply terminal is connected to the power supply.

[0071] Optionally, the observation terminal is pre-installed with Matlab software, and the images captured by the camera are recognized, analyzed, and the results displayed through the Matlab software.

[0072] Optionally, the observation terminal is an observation computer.

[0073] Optionally, the camera is an industrial-grade camera with a resolution of not less than 1080P and a shooting frame rate of 200fps~500fps.

[0074] Optionally, the test loop acquisition system includes the monitoring instrument, the instrument control cabinet, the instrument control acquisition system, and the parameter display terminal connected in sequence. The instrument control acquisition system supports the acquisition of analog and digital signals. The parameter display terminal has a DCS control system and stores the monitoring data obtained by the monitoring instrument to a local server.

[0075] Optionally, the process of the medium-pressure small temperature difference evaporation test circuit device during testing is as follows:

[0076] S1, Pre-test preparation: The steam generator in the hot-side tube circuit is injected with medium to the target liquid level; the cold-side closed circuit in the cold-side shell circuit is injected with medium and vented; the sealing parts of each circuit and the status of the monitoring instruments are checked to ensure that the equipment is normal.

[0077] S2, Hot-side heating and pressurization: Start the steam generator to heat and pressurize, heat to the first preset temperature, discharge the non-condensable gas in the steam generator, and continue to heat and pressurize the steam generator to the test target condition. The steam generated by the steam generator is regulated by each regulating valve in the hot-side pipe circuit to adjust the hot-side pressure and flow rate to the hot-side operating condition target value.

[0078] S3, Cold-side heating and pressurization: Start the circulating main pump and electric heater in the cold-side shell-side circuit to heat the cold-side medium to the second preset temperature. Adjust the cold-side circuit pressure to the first preset pressure through the siphon tank in the cold-side shell-side circuit. When the temperature difference and pressure difference between the cold-side closed circuit and the cold-side shell-side of the test prototype are within the preset range, switch the test circuit pipeline to connect the cold-side shell-side circuit with the cold-side shell-side of the test prototype. Continue to heat and pressurize the cold-side shell-side circuit to the target value of the test conditions. During the test, maintain the liquid level of the cold-side shell-side of the test prototype at the target value and keep it stable to ensure the stability of the test conditions.

[0079] S4, Test Operation: The slightly superheated steam in the hot-side tube circuit is introduced into the hot-side tube of the test prototype to exchange heat with the cold-side shell medium of the test prototype. The hot and cold side parameters are adjusted in real time to keep the superheat of the tube bundle wall of the test prototype stable at ≤4℃, maintain stable operation of the test conditions, and run for no less than the preset time. During the test, at least one parameter among temperature, pressure, flow rate, liquid level and wall temperature of each preset monitoring point is collected in real time, and the evaporation flow pattern change process is captured simultaneously.

[0080] S5, Test End: In the hot-side tube circuit, gradually reduce the heating power of the steam generator and depressurize the steam generator to achieve temperature and pressure reduction; in the cold-side shell circuit, gradually reduce the heating power of the electric heater, preferably in conjunction with the main cooler to achieve temperature and pressure reduction; during the test, control the cooling rate of each circuit to ≤50℃ / h and the pressure reduction rate to ≤0.2MPa / min. After the temperature of each circuit drops to the third preset temperature and the pressure drops to atmospheric pressure, safely shut down the test device, and the test ends.

[0081] Beneficial effects: The present invention has at least one or more of the following advantages:

[0082] 1. This invention adopts an independent dual-loop structure design with a closed loop on the cold side and an open loop on the hot side, realizing independent control of the heat source output on the hot side and the evaporation process on the cold side. There is no medium interference on the cold and hot sides, avoiding the problem of mutual interference between the cold and hot sides. It can accurately match the pressure and temperature parameters of the cold and hot sides for medium-pressure, small-temperature-difference evaporation, and solves the problem of poor adaptability of existing loop operating conditions.

[0083] 2. This invention incorporates a siphon tank in a closed-loop circuit on the cold side. Through the siphon principle, it achieves automatic liquid level compensation (e.g., ±5mm), solving the problem of unstable wall overheating caused by pressure fluctuations and liquid level imbalances in small temperature difference tests, thus ensuring the accuracy of test data. Furthermore, the siphon tank integrates both nitrogen pressure stabilization and liquid level compensation functions, allowing for precise pressure stabilization on the cold side (e.g., ±0.01MPa) through nitrogen volume ratio adjustment.

[0084] 3. The prototype of this invention is equipped with a scaled-down tube bundle that matches the medium-pressure evaporator of Hualong One inside the evaporation chamber, and has a high-temperature and high-pressure quartz glass window. The scaled-down tube bundle accurately reproduces the heat transfer characteristics of the actual evaporator. The window, together with a visualization observation device, enables real-time observation of the flow state, which solves the problem that the existing test circuit cannot simulate the actual heat transfer process and has no flow state observation capability.

[0085] 4. The test prototype of this invention is equipped with a high-precision acquisition component adapted to small temperature difference conditions, which can realize high-precision measurement of wall temperature (e.g., ±0.5℃), medium temperature (e.g., ±0.1%), pressure (e.g., ±0.1%), and flow rate (e.g., 0.5 grade), solving the problem of insufficient measurement accuracy of existing loops and providing reliable data for the analysis of small temperature difference heat transfer characteristics.

[0086] 5. The test prototype of this invention adopts a DCS instrumentation and control system and is electrically connected to all execution components and data acquisition instruments to realize automatic parameter control and deviation compensation. The test parameters can be monitored and automatically adjusted in real time, with high control accuracy and fast response speed, ensuring that the wall superheat is stable at ≤4℃. The test conditions can be stably operated for no less than 30 minutes, which solves the problems of low accuracy and poor stability of existing circuit manual adjustment.

[0087] 6. This invention can stably reproduce the core parameters of the small temperature difference evaporation of the Hualong One medium-pressure evaporator (heating steam pressure 5.5~6.5MPa, evaporation pressure 5.0~5.5MPa, wall superheat ≤4℃), with pressure control accuracy of ±0.01MPa, temperature control accuracy of ±1℃, and liquid level control accuracy of ±5mm, which is far superior to existing test circuits and can meet the test verification requirements of medium-pressure small temperature difference evaporation technology.

[0088] 7. This invention integrates multiple functions such as working condition simulation, data acquisition, flow state observation, and parameter control. It can simulate various test conditions such as constant wall superheat, matrix combination, variable load, and constant heat flux density. Moreover, the parameters on both the hot and cold sides can be independently controlled, which solves the problem that the existing test loops have only one function and cannot meet the needs of comprehensive test verification.

[0089] 8. This invention fills the technical gap in medium-pressure small temperature difference evaporation test circuit devices at home and abroad, and provides a dedicated and reliable test platform for the research, design and performance verification of small temperature difference evaporation technology of Hualong One medium-pressure evaporator. The test data can directly guide the structural optimization and operation debugging of actual products. Attached Figure Description

[0090] Figure 1 This is a schematic diagram of an overall structure of the present invention;

[0091] Figure 2 for Figure 1 A partially enlarged view of the hot-side tube circuit in the image;

[0092] Figure 3 for Figure 2 A partially enlarged view of the cold-side shell-side loop in the circuit;

[0093] Figure 4 This is a schematic diagram showing the arrangement of key monitoring points of the prototype of the present invention;

[0094] Figure 5 This is a schematic diagram of the structure of the visualization observation device of the present invention;

[0095] Figure 6 This is a schematic diagram of the experimental loop acquisition system of the present invention. Detailed Implementation

[0096] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so as to better understand the purpose, features and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are only for illustrating the essential spirit of the technical solution of the present invention.

[0097] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that the embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0098] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0099] In the following description, in order to clearly demonstrate the structure and operation of the present invention, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0100] Reference Figures 1 to 3 This invention provides a medium-pressure small temperature difference evaporation test circuit device, which includes a hot-side tube-side circuit and a cold-side shell-side circuit. The hot-side tube-side circuit and the cold-side shell-side circuit are independent of each other, so that the medium-pressure small temperature difference evaporation test circuit device of this invention forms an independent circulation structure design for the hot and cold sides.

[0101] The hot-side tube-side loop is an open loop, and heat exchange occurs between the hot-side tube-side loop and the hot-side tube-side loop of the prototype. The cold-side shell-side loop is a closed loop, and heat exchange occurs between the cold-side shell-side loop and the cold-side shell-side loop of the prototype.

[0102] This invention adopts an independent dual-loop structure design with a closed loop on the cold side and an open loop on the hot side, realizing independent control of the heat source output on the hot side and the evaporation process on the cold side. There is no medium interference on the hot and cold sides, avoiding the problem of mutual interference between the hot and cold sides. It can accurately match the pressure and temperature parameters of the hot and cold sides for medium-pressure, small-temperature-difference evaporation, and solves the problem of poor adaptability of existing loops.

[0103] In one embodiment, the hot-side tube-side loop is an open loop, which uses a process of "steam generation-superheating-heat exchange-drainage" to provide a heat source for the cold-side shell-side closed loop (i.e., the cold-side shell-side loop), simulating the heating steam heat exchange process of the evaporator tube side. This is used to achieve independent control of the hot-side pressure, temperature, and flow rate, without any medium interference with the cold-side shell-side loop, thus ensuring the stability of the heat source output.

[0104] Reference Figure 1 and Figure 2 The hot-side pipe circuit includes a steam generator 1, a steam pipe heater 2, a condensate tank 3, a hot-side silencer 4, a first shut-off valve 21, a steam vortex flow meter 31, an outlet pipeline balance flow meter 32, a first regulating valve 61, a second regulating valve 62, and a third regulating valve 63.

[0105] Steam generator 1 is used to generate saturated steam. The outlet of steam generator 1 is connected in sequence via pipeline to first shut-off valve 21, first regulating valve 61, steam pipeline heater 2, steam vortex flow meter 31 and hot-side tube inlet of test prototype 7.

[0106] The inlet of the condensate tank 3 is connected via a pipeline to the hot-side outlet of the prototype 7. The bottom outlet of the condensate tank 3 is connected via a pipeline to the outlet pipeline balance flow meter 32, the second regulating valve 62, the third regulating valve 63, and the hot-side silencer 4. By arranging the condensate tank 3 downstream of the hot-side outlet of the prototype 7, this invention effectively collects the condensate generated in the hot-side outlet pipeline of the prototype 7. Furthermore, it prevents residual steam from overflowing with the condensate, achieving vapor-liquid separation and avoiding steam loss.

[0107] In the hot-side tube circuit of this invention, the high-temperature and high-pressure steam source is provided by the steam generator 1. After passing through the first shut-off valve 21 and the first regulating valve 61 set on the pipeline, the steam flows through the steam pipeline heater 2 and then enters the steam vortex flow meter 31 to monitor the steam inlet flow rate into the hot-side tube inlet side of the test prototype 7. After heat exchange inside the test prototype 7, the steam flows out through the hot-side tube outlet side of the test prototype 7 to the condensate tank 3. The high-temperature and high-pressure saturated water at the bottom outlet of the condensate tank 3 flows out to the outlet pipeline balance flow meter 32. The condensate flow rate is monitored in real time by the outlet pipeline balance flow meter 32, and the heat exchange between the hot and cold sides is calculated by the condensate flow rate. The second regulating valve 62 and the third regulating valve 63 are arranged downstream of the outlet pipeline balance flow meter 32 to control the flow rate and pressure relief of the loop pipeline. Finally, the steam flows through the hot-side silencer 4 and is discharged to the outdoor atmospheric environment.

[0108] In one embodiment, the steam generator 1 is a hot-side steam generating unit, the design pressure of the steam generator 1 is 9.0 MPa, and the design temperature of the steam generator 1 is 320°C.

[0109] In one embodiment, reference is made to Figure 1 and Figure 2 The bottom of the steam generator 1 is provided with a first electric heating rod 1-1, and the heating power of the first electric heating rod 1-1 is preferably 500 kW.

[0110] The medium inside the steam generator 1 is heated and pressurized by the first electric heating rod 1-1 to generate saturated steam, providing a basic steam source for the experiment.

[0111] In one embodiment, reference is made to Figure 1 and Figure 2 The top of the steam generator 1 is connected in sequence to the first safety valve 1-2 and the pressure relief regulating valve 64 via pipelines.

[0112] The first safety valve 1-2 has an overpressure protection function to ensure safe operation. During the test, the pressure of the steam generator 1 is regulated and controlled by the heating power of the electric heating rod 1-1 and the pressure relief regulating valve 64.

[0113] In one embodiment, a steam pipe heater 2 is arranged upstream of the hot-side tube inlet of the test prototype 7, and the heating power of the steam pipe heater 2 is 15kW. The pipeline between the first regulating valve 61 and the steam vortex flow meter 31 can be referred to as the steam pipe. The steam pipe heater 2 is wrapped around the outer wall of the steam pipe to heat the saturated steam into slightly superheated steam, accurately control the hot-side steam inlet temperature (e.g., 270℃~280℃), meet the test temperature requirements, reduce heat loss, and ensure steam quality.

[0114] In one embodiment, reference is made to Figure 1 and Figure 2 The top of the condensate tank 3 is connected to the hot-side tube inlet of the test prototype 7 via a steam balance pipeline.

[0115] The pressure balance between the condensate tank 3 and the hot side of the test prototype 7 is achieved through the steam balance pipeline (or steam balance pipe), which plays a role in stabilizing the pressure.

[0116] In one embodiment, a level gauge is arranged on the hydrophobic tank 3 for level monitoring.

[0117] In one embodiment, the hot-side tube outlet back pressure of the test prototype 7 is the core component for hot-side tube circuit pressure regulation. The hot-side tube circuit regulates the hot-side pressure of the test prototype 7 through the first regulating valve 61, the second regulating valve 62, the third regulating valve 63, and the steam pressure in the steam generator 1.

[0118] In practice, the hot-side pressure adjustment range is 5.0 MPa to 6.5 MPa.

[0119] In one embodiment, the hot-side tube circuit controls the hot-side steam flow rate of the hot-side tube circuit through a first regulating valve 61, a second regulating valve 62, and a third regulating valve 63.

[0120] In practice, the hot-side flow rate is controlled within the range of 0.25 t / h to 1.2 t / h.

[0121] In one embodiment, the cold-side shell-side loop is a closed loop, which is the core simulation unit for small temperature difference evaporation and is used to realize the water evaporation process in the shell side of the evaporator.

[0122] Reference Figure 1 and Figure 3 The cold-side shell-side circuit includes a circulating main pump 5, an electric heater 6, a mixer 11, a siphon tank 12, a fourth shut-off valve 24, a fifth shut-off valve 25, a main circuit pipeline balance flow meter 33, a bypass branch pipeline Venturi flow meter 34, a main circuit pipeline regulating valve 41, a bypass branch pipeline regulating valve 42, a fourth regulating valve 44, a cold-side shell-side inlet pipeline isolation valve 51, and a cold-side shell-side outlet pipeline isolation valve 53.

[0123] The outlet of the circulating main pump 5 is connected in sequence via pipeline to the main circuit pipeline regulating valve 41, the main circuit pipeline balancing flow meter 33, the electric heater 6, the cold side shell-side inlet pipeline isolation valve 51, and the cold side shell-side inlet of the test prototype 7. The outlet of the circulating main pump 5 is also connected in sequence via pipeline to the bypass branch pipeline Venturi flow meter 34, the bypass branch regulating valve 42, and the subcooling water inlet of the mixer 11.

[0124] The cold-side shell-side outlet of the prototype 7 is connected in sequence via pipeline to the cold-side shell-side outlet pipeline isolation valve 53, the fourth regulating valve 44, and the steam inlet of the mixer 11. The outlet of the mixer 11 is connected in sequence via pipeline to the fourth shut-off valve 24 and the inlet of the siphon tank 12. The outlet of the siphon tank 12 is connected in sequence via pipeline to the fifth shut-off valve 25 and the inlet of the circulating main pump 5.

[0125] In this embodiment, the siphon tank 12 is connected to the liquid phase zone after condensation at the outlet of the test prototype 7 through a pipeline. It can automatically compensate for liquid level fluctuations during the test through the siphon principle, realize the liquid level compensation function, and achieve a liquid level control accuracy of ±5 mm, avoiding deviation of the wall overheating caused by liquid level changes.

[0126] In the cold-side shell-side circuit of this invention, high-temperature and high-pressure subcooled water is driven out by the circulating main pump 5. One path passes through the main circuit pipeline regulating valve 41 and the main circuit pipeline balance flow meter 33 to enter the electric heater 6, while the other path passes through the bypass branch pipeline Venturi flow meter 34 and the bypass branch regulating valve 42 to enter the subcooled water inlet side of the mixer 11. The outlet pipeline of the electric heater 6 directly enters the cold-side shell-side inlet side of the test prototype 7 via the cold-side shell-side inlet pipeline isolation valve 51. After heat exchange inside the test prototype 7, the water flows through the test prototype... 7. Steam flows out from the cold side shell-side outlet. The steam from the cold side shell-side outlet of the test prototype 7 flows directly into the steam inlet side of the mixer 11 through the cold side shell-side outlet pipeline isolation valve 53 and the fourth regulating valve 44. The steam and the subcooled water from the bypass branch pipeline are mixed in the mixer 11 and then flow out from the outlet side of the mixer 11. After passing through the fourth shut-off valve 24, the siphon tank 12, and the fifth shut-off valve 25, it flows into the inlet side of the circulating main pump 5 to achieve closed circulation, which can effectively avoid media contamination and pressure loss and ensure the stability of the test conditions.

[0127] In one embodiment, the circulating main pump 5 is a high-temperature and high-pressure vertical canned pump that provides power to the cold-side shell-side circuit. It adopts a variable frequency control design. The cold-side shell-side circuit achieves cold-side flow control by adjusting the variable frequency of the circulating main pump 5 and the opening of the main circuit pipeline regulating valve 41 and the bypass branch regulating valve 42, thereby achieving precise adjustment of liquid level and evaporation rate.

[0128] In practical implementation, the rated flow rate of the main circulating pump 5 is 5 m³ / s. 3 / h and the head is 80m.

[0129] In one embodiment, reference is made to Figure 1 and Figure 3 In the cold-side shell-side circuit of this embodiment, the pipeline between the fifth shut-off valve 25 and the inlet of the circulating main pump 5 is the upstream pipeline of the inlet of the circulating main pump 5 and is divided into two branches. One branch is connected to the fifth regulating valve 45 and the inlet venturi flow meter 37 in sequence via the pipeline from the fifth shut-off valve 25. The other branch is connected to the inlet pipeline balance flow meter 36, the sixth regulating valve 46, the main cooler 14 and the inlet venturi flow meter 37 in sequence via the pipeline from the fifth shut-off valve 25. The inlet venturi flow meter 37 is connected to the inlet of the circulating main pump 5, so that the two branches merge into the inlet of the circulating main pump 5 after passing through the inlet venturi flow meter 37.

[0130] In the cold-side shell-side circuit of this embodiment, the upstream pipeline of the circulating main pump 5 inlet is divided into two branches. One branch flows directly out through the fifth regulating valve 45, and the other heat exchange branch flows through the inlet pipeline balance flow meter 36 and the sixth regulating valve 46 before entering the main cooler 14 for heat exchange and then flowing out. The two pipelines flow into the inlet venturi flow meter 37 after merging, and then into the inlet side of the circulating main pump 5.

[0131] In one embodiment, reference is made to Figure 1 and Figure 3 The siphon tank 12 is filled with nitrogen gas, which flows out through the nitrogen cylinder group 13. The nitrogen cylinder group 13 is connected in sequence to the check valve 28, the seventh shut-off valve 27 and the top of the siphon tank 12 via the nitrogen filling pipeline.

[0132] In one embodiment, reference is made to Figure 1 and Figure 3 An exhaust valve 26 is connected to the nitrogen filling pipeline between the seventh shut-off valve 27 and the siphon tank 12, which can realize the pressure relief function.

[0133] In one embodiment, reference is made to Figure 1 and Figure 3 A second electric heating rod 12-1 is arranged at the bottom of the siphon tank 12 to heat the medium inside the siphon tank 12.

[0134] The pressure stabilization function of the cold side shell circuit can be achieved by heating the medium in the siphon tank 12 with the heating power of the second electric heating rod 12-1 arranged at the bottom of the siphon tank 12, and by adjusting the volume ratio of nitrogen to water through the nitrogen filling pipeline. Both can be controlled independently to compensate for system pressure fluctuations.

[0135] In one embodiment, reference is made to Figure 1 and Figure 3 The top of the siphon tank 12 is connected to the second safety valve 12-2, which has an overpressure protection function to ensure safe operation.

[0136] In one embodiment, reference is made to Figure 1 and Figure 3 The outlet of the electric heater 6 is also connected in sequence to the second isolation valve 52 and the fourth regulating valve 44 via pipeline.

[0137] This causes the outlet pipeline of the electric heater 6 to split into two branches. One branch flows directly into the cold side shell-side inlet side of the test prototype 7 through the isolation valve 51 of the cold side shell-side inlet pipeline, while the other branch bypasses the test prototype 7 and flows directly into the inlet side of the loop mixer 11.

[0138] The medium-pressure, small-temperature-difference evaporation test circuit device has the function of switching between independent operation of the cold-side closed circuit and connected operation of the cold-side shell side of the test prototype 7:

[0139] The temperature and pressure increase of the cold-side shell side of the test prototype 7 can be achieved by closing the inlet and outlet of the cold-side shell side, i.e., closing the isolation valve 51 of the cold-side shell side inlet pipeline and the isolation valve 53 of the cold-side shell side outlet pipeline. Heat exchange is then performed on the subcooled water in the cold-side shell side of the test prototype 7 through the hot-side pipe loop to achieve the temperature and pressure increase of the cold-side shell side of the test prototype 7.

[0140] The cold-side closed loop heating and pressurization is achieved through the outlet branch pipeline of the electric heater 6 and the loop bypass branch. That is, the second isolation valve 52 is opened, and the cold-side closed loop is heated and the loop temperature and pressure are increased through the circulating main pump 5, the main loop pipeline regulating valve 41, the bypass branch regulating valve 42 and the electric heater 6. The closed-loop operation of the cold-side closed loop is achieved through the loop outlet pipeline connected to the siphon tank 12.

[0141] When the temperature and pressure rise of the closed loop on the cold side are close to those of the cold side shell side of the test prototype 7, that is, when the temperature difference and pressure difference between the two are within the preset range, the isolation valve 51 of the cold side shell side inlet pipeline and the isolation valve 53 of the cold side shell side outlet pipeline are opened, and the second isolation valve 52 is closed, so as to realize the connection between the cold side closed loop and the cold side shell side of the test prototype 7.

[0142] In one embodiment, reference is made to Figure 1 and Figure 3 The cold-side shell-side circuit also includes a vapor-liquid separator 8. The inlet of the vapor-liquid separator 8 is connected to the cold-side shell-side outlet of the test prototype 7 via a pipeline. The outlet of the vapor-liquid separator 8 is connected in sequence via a pipeline to a heat exchanger 9, an outlet pipeline regulating valve 43, an outlet venturi flow meter 35, a third shut-off valve 23, and a fourth shut-off valve 24.

[0143] In the cold-side shell-side loop of this embodiment, in order to ensure loop stability and reduce the fluctuation of vapor-liquid two-phase mixing, the cold-side shell-side outlet steam of the test prototype 7 is divided into two branches. One branch flows through the cold-side shell-side outlet pipeline isolation valve 53 and the fourth regulating valve 44 and directly enters the steam inlet side of the mixer 11. The other branch flows through the vapor-liquid separator 8, and after heat exchange and condensation through the heat exchanger 9, it merges into the outlet side of the mixer 11 through the outlet pipeline regulating valve 43, the outlet venturi flow meter 35, and the third shut-off valve 23. The two pipelines merge at the outlet side of the mixer 11.

[0144] In one embodiment, heat exchanger 9 is a microchannel heat exchanger.

[0145] In one embodiment, reference is made to Figure 1 and Figure 3 A drain and pressure relief pipeline is arranged at the bottom of the vapor-liquid separator 8. The bottom of the vapor-liquid separator 8 is connected in sequence to the second shut-off valve 22, the seventh regulating valve 47 and the cold side silencer 10 via the drain and pressure relief pipeline.

[0146] In this embodiment, a drain and pressure relief pipeline is arranged at the bottom of the vapor-liquid separator 8. After the pipeline is equipped with a second shut-off valve 22 and a seventh regulating valve 47, it is discharged to the outdoor atmospheric environment through a cold-side silencer 10. It can be used to separate the saturated vapor and unevaporated liquid water generated in the shell side of the test prototype 7.

[0147] In one embodiment, each regulating valve in the medium-pressure small-temperature-difference evaporation test loop device has a pipeline flow regulation function, each isolation valve in the medium-pressure small-temperature-difference evaporation test loop device has a pipeline system isolation function, and the driving mode of each regulating valve and each isolation valve in the medium-pressure small-temperature-difference evaporation test loop device are all electric valves.

[0148] Reference Figures 1 to 3 , the first regulating valve 61, the second regulating valve 62, the third regulating valve 63, the pressure relief regulating valve 64, the main loop pipeline regulating valve 41, the bypass branch regulating valve 42, the outlet pipeline regulating valve 43, the fourth regulating valve 44, the fifth regulating valve 45, the sixth regulating valve 46, and the seventh regulating valve 47 all have a pipeline flow regulation function, and all are driven by electric valves.

[0149] Reference Figures 1 to 3 , the cold side shell side inlet pipeline isolation valve 51, the second isolation valve 52, and the cold side shell side outlet pipeline isolation valve 53 all have a pipeline system isolation function, and all are driven by electric valves.

[0150] In one embodiment, the medium in the system loop including the hot side tube side loop and the cold side shell side loop is deionized water.

[0151] In one embodiment, each pipeline in the system loop including the hot side tube side loop and the cold side shell side loop is made of 304 stainless steel pipes.

[0152] In one embodiment, a scaled tube bundle matching the structure of a preset medium-pressure evaporator is arranged inside the test prototype 7.

[0153] The preset medium-pressure evaporator is preferably a Hualong One medium-pressure evaporator. That is, a scaled tube bundle matching the structure of the Hualong One medium-pressure evaporator is arranged inside the test prototype 7.

[0154] A plurality of visual observation windows are arranged on the cavity of the test prototype 7, and the visual observation windows are preferably quartz glass windows made of high temperature resistant and high pressure resistant materials. The visual observation windows can be equipped with a visual observation device 16 to realize real-time monitoring of the evaporation flow pattern.

[0155] Reference Figure 4 , a first visual observation window 7-1, a second visual observation window 7-2 and a third visual observation window 7-3 are opened on the cavity of the test prototype 7.

[0156] Monitoring instruments for monitoring at least one parameter selected from temperature, pressure and liquid level are arranged on the inlet and outlet pipelines of the hot side tube pass and cold side shell pass of the test prototype 7 and on the cavity of the test prototype 7, and the monitoring instruments and the equipment control signals of the test prototype 7 are all connected to the test loop acquisition system 17, so as to realize real-time data acquisition, control and storage.

[0157] In one embodiment, a tube bundle wall temperature measuring instrument is arranged on the outer wall surface of the heat transfer tube of the prototype 7.

[0158] In one embodiment, the tube bundle wall temperature measuring instrument is an N-type thermocouple.

[0159] In one embodiment, the tube bundle wall temperature measuring instrument is an A-grade instrument with a calibration error of ±0.5℃ and a spacing of 1000mm between adjacent temperature measuring points.

[0160] In one embodiment, each region of the heat transfer tube bundle bend section and straight section section of the cold side shell side of the test prototype 7 is provided with two cold side shell side visualization observation windows, one of which is a supplementary light source window and the other is a shooting window.

[0161] Reference Figure 4 The test prototype 7 is equipped with two cold-side shell-side visualization observation windows, 7-1 and 7-2, located in the bend section and straight section of the heat transfer tube bundle, respectively, with two windows in each section, for a total of four. Among them, windows 7-1-a and 7-2-a are supplementary light source windows, while windows 7-1-b and 7-2-b are imaging windows.

[0162] The supplementary light source window provides an additional light source for the visualization observation device 16, and the shooting window provides a high-speed camera shooting window for the visualization observation device 16.

[0163] In one embodiment, the hot-side tube outlet tube box area of ​​the test prototype 7 is provided with three hot-side tube visualization windows, one of which is a supplementary light source window, and the other two are shooting windows, which are symmetrically distributed on the front and rear sides of the hot-side tube outlet tube box of the test prototype 7.

[0164] Reference Figure 4 The hot-side tube-side visualization window 7-3 is arranged in the tube-side outlet tube box area. There are a total of 3 windows, of which window 7-3-a is a supplementary light source window, and the remaining 2 windows 7-3-b are symmetrically distributed on the front and rear sides of the hot-side tube-side outlet tube box of the test prototype 7.

[0165] The supplementary light source window provides an additional light source for the visualization observation device 16, and the shooting window provides a high-speed camera shooting window for the visualization observation device 16.

[0166] In one embodiment, the monitoring instruments include at least one of the following: a hot-side temperature monitoring instrument for monitoring the inlet and outlet temperatures of the hot-side tubes of the prototype 7; a hot-side pressure monitoring instrument for monitoring the inlet and outlet pressures of the hot-side tubes of the prototype 7; a cold-side temperature monitoring instrument for monitoring the inlet and outlet temperatures of the cold-side shell of the prototype 7; a cold-side pressure monitoring instrument for monitoring the inlet and outlet pressures of the cold-side shell of the prototype 7; a vapor phase temperature monitoring instrument for monitoring the vapor phase temperature of the prototype 7; a vapor phase pressure monitoring instrument for monitoring the vapor phase pressure of the prototype 7; a liquid phase temperature monitoring instrument for monitoring the liquid phase temperature of the prototype 7; a liquid phase pressure monitoring instrument for monitoring the liquid phase pressure of the prototype 7; and a liquid level monitoring instrument for monitoring the liquid level of the prototype 7.

[0167] In one embodiment, both the hot-side temperature monitoring instrument and the cold-side temperature monitoring instrument are platinum resistance thermometers with an accuracy of 1 / 3B class and a calibration error of ±0.1%.

[0168] In one embodiment, both the vapor phase temperature monitoring instrument and the liquid phase temperature monitoring instrument use type E thermocouples with an accuracy of Class A.

[0169] In one embodiment, in order to ensure that the test process accurately reflects the accuracy of the temperature measurement of the test prototype 7, each temperature monitoring point in the test prototype 7 is equipped with two temperature monitoring instruments.

[0170] Reference Figure 4 The monitoring instruments include a first hot-side temperature monitoring instrument 701 for monitoring the inlet temperature of the hot-side tube side of the test prototype 7, and a second hot-side temperature monitoring instrument 704 for monitoring the outlet temperature of the hot-side tube side of the test prototype 7. The first hot-side temperature monitoring instrument 701 has two temperature monitoring instruments, namely temperature monitoring instrument T1a and temperature monitoring instrument T1b. The second hot-side temperature monitoring instrument 704 has two temperature monitoring instruments, namely temperature monitoring instrument T2a and temperature monitoring instrument T2b.

[0171] Reference Figure 4 The monitoring instruments include a first cold-side temperature monitoring instrument 705 for monitoring the inlet temperature of the cold-side shell side of the test prototype 7, and a second cold-side temperature monitoring instrument 708 for monitoring the outlet temperature of the cold-side shell side of the test prototype 7. The first cold-side temperature monitoring instrument 705 has two temperature monitoring instruments, namely temperature monitoring instrument T3a and temperature monitoring instrument T3b. The second cold-side temperature monitoring instrument 708 has two temperature monitoring instruments, namely temperature monitoring instrument T4a and temperature monitoring instrument T4b.

[0172] Reference Figure 4The monitoring instruments include a first vapor phase temperature monitoring instrument 709 and a second vapor phase temperature monitoring instrument 711 for monitoring the vapor phase temperature of the test prototype 7, and a first liquid phase temperature monitoring instrument 713 and a second liquid phase temperature monitoring instrument 715 for monitoring the liquid phase temperature of the test prototype 7.

[0173] In one embodiment, the hot-side pressure monitoring instrument, the cold-side pressure monitoring instrument, the vapor phase pressure monitoring instrument, and the liquid phase pressure monitoring instrument all use RoseMount2088 pressure transmitters with an accuracy of ±0.1%.

[0174] Reference Figure 4 The monitoring instruments include a first hot-side pressure monitoring instrument 702 for monitoring the inlet pressure of the hot-side tube side of the test prototype 7, a second hot-side pressure monitoring instrument 703 for monitoring the outlet pressure of the hot-side tube side of the test prototype 7, a first cold-side pressure monitoring instrument 706 for monitoring the inlet pressure of the cold-side shell side of the test prototype 7, a second cold-side pressure monitoring instrument 707 for monitoring the outlet pressure of the cold-side shell side of the test prototype 7, a first vapor phase pressure monitoring instrument 710 and a second vapor phase pressure monitoring instrument 712 for monitoring the vapor phase pressure of the equipment of the test prototype 7, and a first liquid phase pressure monitoring instrument 714 and a second liquid phase pressure monitoring instrument 716 for monitoring the liquid phase pressure of the equipment of the test prototype 7. All of the above pressure monitoring instruments use RoseMount2088 pressure transmitters with an accuracy of ±0.1%.

[0175] In one embodiment, each pressure monitoring point in the test prototype 7 used to monitor the vapor and liquid phase pressures of the equipment is equipped with two pressure monitoring instruments.

[0176] In one embodiment, there are two liquid level monitoring instruments, namely a magnetic float liquid level gauge and a differential pressure liquid level gauge, which enables the test prototype 7 to form a dual liquid level measurement mode, thereby achieving accurate liquid level monitoring and redundant protection.

[0177] The magnetic level gauge is preferably 0~0.8m in range, and the differential pressure level gauge is preferably a RoseMount3051 pressure transmitter with an accuracy of ±0.1%.

[0178] Reference Figure 4 The cold side shell level of the test prototype 7 adopts a dual level measurement mode using a magnetic float level gauge 717 and a differential pressure level gauge 718.

[0179] In one embodiment, reference is made to Figure 5The visualization observation device 16 includes a camera 161, a supplementary light source 162, a power supply 163, and an observation terminal 164. The camera 161 faces the visualization observation window to capture the internal working conditions of the test prototype 7. The signal output of the camera 161 is transmitted to the observation terminal 164 via a signal cable. The supplementary light source 162 is located on the side of the camera 161 to provide light for the camera's recording. The power supply 163 of the supplementary light source 162 is connected to the power supply 163.

[0180] The visualization observation device 16 in this embodiment can be moved and adjusted according to the position of the window of the test prototype 7, so as to achieve the purpose of real-time observation of different objects in different areas. The visualization observation device 16 can clearly capture the boiling of the bubble nuclei and the flow state change process around the tube bundle, and can also realize the flow state observation of the tube outlet.

[0181] In one embodiment, the observation terminal 164 is pre-installed with Matlab software. The images captured by the camera 161 are intelligently recognized, analyzed, and the results are displayed through the Matlab software in order to ultimately obtain the flow state characteristic parameters.

[0182] In one embodiment, the observation terminal 164 is an observation computer. Of course, other terminals with a display interface and human-computer interaction can also be used.

[0183] In one embodiment, the camera 161 is an industrial-grade camera with a resolution of not less than 1080P and a shooting frame rate of 200fps~500fps.

[0184] In one embodiment, reference is made to Figure 6 The test loop acquisition system 17, serving as the core of data acquisition for the test loop, includes a monitoring instrument 171, an instrument control cabinet 172, an instrument control acquisition system 173, and a parameter display terminal 174 connected in sequence. The instrument control acquisition system 173 supports the acquisition of both analog and digital signals. The parameter display terminal 174 has a DCS control system to better adapt to the high-precision measurement requirements of medium-pressure, small-temperature-difference evaporation tests. The parameter display terminal 174 stores the monitoring data obtained from the monitoring instrument 171 to a local server.

[0185] The test loop acquisition system 17 in this embodiment adopts a DCS control system, which supports the acquisition of analog and digital signals, manual / automatic dual-mode control, and can convert all measurement data into digital signals, store them in a local server, and transmit them in real time, which facilitates parameter monitoring and subsequent data analysis during the test.

[0186] In one embodiment, the process of conducting a test using the device of the present invention is as follows:

[0187] S1, Preparations before the test: Inject the medium into the steam generator 1 in the hot-side tube circuit to the target liquid level; Inject the medium into the cold-side closed circuit in the cold-side shell circuit and vent the air, check the sealing parts of each circuit and the status of the monitoring instruments to ensure that the equipment is in normal working order.

[0188] S2, Hot side heating and pressurization: Start steam generator 1 to heat and pressurize, heat to the first preset temperature, discharge non-condensable gas in steam generator 1, continue to heat and pressurize steam generator 1 to the test target condition, the steam generated by steam generator 1 is adjusted by each regulating valve in the hot side pipe circuit to adjust the hot side pressure and flow rate to the hot side operating condition target value.

[0189] S3, Cold Side Heating and Pressurization: Start the circulating main pump 5 and electric heater 6 in the cold side shell-side circuit to heat the cold side medium to the second preset temperature. Adjust the cold side circuit pressure to the first preset pressure through the siphon tank 12 in the cold side shell-side circuit. When the temperature difference and pressure difference between the cold side closed circuit and the cold side shell-side of the test prototype 7 are within the preset range, switch the test circuit pipeline to connect the cold side shell-side circuit with the cold side shell-side of the test prototype 7. Continue to heat and pressurize the cold side shell-side circuit to the target value of the test conditions. During the test, keep the liquid level of the cold side shell-side of the test prototype 7 at the target value and keep it stable to ensure the stability of the test conditions.

[0190] S4, Test Operation: The slightly superheated steam in the hot-side tube circuit is introduced into the hot-side tube of the test prototype 7 to exchange heat with the cold-side shell medium of the test prototype 7. The hot and cold side parameters are adjusted in real time to keep the superheat of the tube bundle wall of the test prototype stable at ≤4℃, maintain stable operation of the test conditions, and the running time is not less than the preset duration. During the test, at least one parameter among temperature, pressure, flow rate, liquid level and wall temperature of each preset monitoring point is collected in real time, and the evaporation flow pattern change process is captured simultaneously.

[0191] S5, Test End: In the hot-side tube circuit, gradually reduce the heating power of the steam generator 1 and depressurize the steam generator 1 to achieve temperature and pressure reduction; in the cold-side shell circuit, gradually reduce the heating power of the electric heater 6, preferably in conjunction with the main cooler 14 to achieve temperature and pressure reduction; during the test, control the cooling rate of each circuit to ≤50℃ / h and the pressure reduction rate to ≤0.2MPa / min. After the temperature of each circuit drops to the third preset temperature and the pressure drops to atmospheric pressure, safely shut down the test device and the test ends.

[0192] Example 1:

[0193] Reference Figures 1 to 6 The working process of the medium-pressure, small-temperature-difference evaporation test circuit device is as follows:

[0194] (1) Preparation before the test: Fill the hot side steam generator 1 with water to the target liquid level, fill the cold side closed loop with water and vent the air, check the sealing parts of the loop and the status of the instruments to ensure that the equipment is normal;

[0195] (2) Heating and pressurizing on the hot side: Start the electric heating rod 1-1 of the steam generator 1 to heat up and pressurize. Heat up to 100 ℃, open the pressure relief regulating valve 25 to discharge the non-condensable gas in the steam generator 1, and then close the pressure relief regulating valve 25. Continue to heat up and pressurize to the test target condition. The generated steam is adjusted to the target value of the hot side condition by the first regulating valve 61, the second regulating valve 62 and the third regulating valve 63.

[0196] (3) Cold side heating and pressurization: Start the cold side closed loop circulation main pump 5 and electric heater 6 to heat the cold side medium to 250℃~260℃. Adjust the cold side loop pressure to 5.0 MPa~5.3 MPa through the siphon tank 12. When the cold side loop temperature and pressure are close to the cold side shell side temperature and pressure of the test prototype 7, switch the test loop pipeline to connect the cold side shell side of the test prototype 7 and continue to steadily heat and pressurize to the target value of the test conditions. During the test, keep the liquid level of the cold side shell side of the test prototype 7 stable to the target value to ensure the stability of the test conditions.

[0197] (4) Test conditions: The hot side slightly superheated steam is introduced into the tube side of the test prototype 7 to exchange heat with the cold side shell side medium. The hot and cold side parameters are adjusted in real time through the test loop acquisition system 17 to keep the superheat of the tube bundle wall of the test prototype 7 stable at ≤4 ℃, maintain stable operation of the test conditions, and run for no less than 30 min. During the test, data such as temperature, pressure, flow rate, liquid level, and wall temperature are collected in real time, and the evaporation flow pattern change process is captured simultaneously through the visualization observation device 16.

[0198] (5) Test completion: The heating power of the electric heating rod 1-1 of the steam generator 1 is gradually reduced in the hot-side loop, and the temperature and pressure are reduced slowly through the pressure relief regulating valve 25; the temperature and pressure are reduced slowly in the cold-side closed loop by gradually reducing the heating power of the electric heater 6 and cooperating with the main cooler 14 of the loop. During the test, the cooling rate is controlled to be ≤50℃ / h and the pressure reduction rate is ≤0.2MPa / min. After the loop temperature drops below 60℃ and the pressure drops to atmospheric pressure, the key equipment of the test device is safely shut down, and the test ends.

[0199] The experimental circuit device can meet the following design parameters: heating steam pressure 5.5 MPa ~ 6.5 MPa, evaporation pressure 5.0 MPa ~ 5.5 MPa, wall superheat ≤ 4℃, cold side rated steam production 1 t / h, and hot side rated steam flow 1.03 t / h.

[0200] This test loop device can simulate various small temperature difference evaporation test conditions such as constant wall superheat, matrix combination, variable load, and constant heat flux density. All test parameters can be independently adjusted, meeting the comprehensive test verification needs of medium-pressure small temperature difference evaporation technology.

[0201] The preferred embodiments of the present invention have been described in detail above. However, it should be understood that after reading the above teachings, those skilled in the art can make various alterations or modifications to the present invention. These equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A medium-pressure, small-temperature-difference evaporation test circuit device, characterized in that, The medium-pressure, small-temperature-difference evaporation test circuit device includes: The hot-side tube-side loop is an open loop, and the hot-side tube-side loop exchanges heat with the hot-side tube-side of the test prototype. The cold-side shell-side loop is a closed loop, and the cold-side shell-side loop exchanges heat with the cold-side shell-side of the test prototype.

2. The medium-pressure small temperature difference evaporation test circuit device as described in claim 1, characterized in that, The hot-side tube circuit includes: A steam generator is used to generate saturated steam. The outlet of the steam generator is connected in sequence via pipeline to a first shut-off valve, a first regulating valve, a steam pipeline heater, a steam vortex flow meter, and the hot-side tube inlet of the test prototype. A condensate tank is provided, with its inlet connected via a pipeline to the hot-side outlet of the test prototype. The bottom outlet of the condensate tank is connected via a pipeline to an outlet pipeline balance flow meter, a second regulating valve, a third regulating valve, and a hot-side silencer.

3. The medium-pressure small temperature difference evaporation test circuit device as described in claim 2, characterized in that, The steam generator is a hot-side steam generation unit, the design pressure of the steam generator is 9.0 MPa, and the design temperature of the steam generator is 320℃. And / or, a first electric heating rod is arranged at the bottom of the steam generator to heat the medium inside the steam generator in order to generate saturated steam; And / or, the top of the steam generator is connected in sequence via pipeline to a first safety valve and a pressure relief regulating valve; And / or, the heating power of the steam pipe heater is 15kW, and the steam pipe heater is enveloped on the outer wall of the pipeline between the first regulating valve and the steam vortex flow meter; And / or, the top of the hydrophobic tank is connected to the hot-side tube inlet of the test prototype via a vapor balance pipeline; And / or, a level gauge is arranged on the hydrophobic tank for level monitoring; And / or, the hot-side tube circuit controls the hot-side pressure at the hot-side tube outlet back pressure of the test prototype through the first regulating valve, the second regulating valve, the third regulating valve, and the steam pressure in the steam generator; And / or, the hot-side tube circuit achieves hot-side flow regulation of the hot-side steam flow through the first regulating valve, the second regulating valve and the third regulating valve.

4. The medium-pressure small temperature difference evaporation test circuit device as described in claim 1, characterized in that, The cold-side shell-side circuit includes: The main circulating pump is connected in sequence via pipeline to the main circuit pipeline regulating valve, the main circuit pipeline balance flow meter, the electric heater, the cold side shell-side inlet pipeline isolation valve, and the cold side shell-side inlet of the test prototype. The mixer, the cold-side shell-side outlet of the prototype is connected in sequence to the cold-side shell-side outlet pipeline isolation valve, the fourth regulating valve and the steam inlet of the mixer via pipeline, and the outlet of the circulating main pump is also connected in sequence to the bypass branch pipeline Venturi flow meter, the bypass branch regulating valve and the subcooled water inlet of the mixer via pipeline. The siphon tank is connected in sequence to the fourth shut-off valve and the inlet of the siphon tank via a pipeline, and the outlet of the siphon tank is connected in sequence to the fifth shut-off valve and the inlet of the circulating main pump via a pipeline.

5. The medium-pressure small temperature difference evaporation test circuit device as described in claim 4, characterized in that, The circulating main pump is a vertical canned pump with variable frequency control design. The cold side shell-side circuit achieves cold side flow control by adjusting the variable frequency of the circulating main pump and the opening of the main circuit pipeline regulating valve and the bypass branch regulating valve. And / or, the pipeline between the fifth shut-off valve and the inlet of the circulating main pump is the upstream pipeline of the circulating main pump inlet and is divided into two branches. One branch is connected to the fifth regulating valve and the inlet Venturi flow meter in sequence via the pipeline from the fifth shut-off valve. The other branch is connected to the inlet pipeline balance flow meter, the sixth regulating valve, the main cooler and the inlet Venturi flow meter in sequence via the fifth shut-off valve. The inlet Venturi flow meter is connected to the inlet of the circulating main pump, so that the two branches merge into the inlet of the circulating main pump after passing through the inlet Venturi flow meter. And / or, the siphon tank is filled with nitrogen, the nitrogen flows out through a nitrogen cylinder group, and the nitrogen cylinder group is connected in sequence to a check valve, a seventh shut-off valve and the top of the siphon tank via a nitrogen filling pipeline; And / or, a second electric heating rod is arranged at the bottom of the siphon tank to heat the medium inside the siphon tank; And / or, a second safety valve is connected to the top of the siphon tank.

6. The medium-pressure small temperature difference evaporation test circuit device as described in claim 4, characterized in that, The outlet of the electric heater is connected in sequence to the second isolation valve and the fourth regulating valve via pipeline; the medium-pressure small temperature difference evaporation test circuit device has the function of switching between independent operation of the cold-side closed circuit and operation connected to the cold-side shell side of the test prototype: The cold-side shell-side inlet pipeline isolation valve and the cold-side shell-side outlet pipeline isolation valve are closed to isolate the test prototype, and the subcooled water in the cold-side shell side of the test prototype is heat-exchanged through the hot-side pipeline loop. The second isolation valve is opened, and the cold-side closed circuit is heated through the circulating main pump, the main circuit pipeline regulating valve, the bypass branch regulating valve and the electric heater. The cold-side closed circuit is also closed-loop operated through the circuit outlet pipeline connected to the siphon tank. When the temperature difference and pressure difference between the cold-side closed loop and the cold-side shell side of the test prototype are within a preset range, the isolation valves of the cold-side shell side inlet pipeline and the cold-side shell side outlet pipeline are opened, and the second isolation valve is closed, thereby connecting the cold-side closed loop with the cold-side shell side of the test prototype.

7. The medium-pressure small temperature difference evaporation test circuit device as described in claim 4, characterized in that, The cold-side shell-side circuit also includes: A vapor-liquid separator, the inlet of which is connected via a pipeline to the cold-side shell-side outlet of the test prototype, and the outlet of which is connected via a pipeline in sequence to a heat exchanger, an outlet pipeline regulating valve, an outlet Venturi flow meter, a third shut-off valve, and a fourth shut-off valve.

8. The medium-pressure small temperature difference evaporation test circuit device as described in any one of claims 1 to 7, characterized in that, Each regulating valve in the medium-pressure small temperature difference evaporation test circuit device has pipeline flow regulation function, each isolation valve in the medium-pressure small temperature difference evaporation test circuit device has pipeline system isolation function, and each regulating valve and each isolation valve in the medium-pressure small temperature difference evaporation test circuit device is driven by electric valves. And / or, the medium in the hot-side tube-side circuit and the medium in the cold-side shell-side circuit are both deionized water; And / or, all pipelines in the hot-side tube-side circuit and the cold-side shell-side circuit are made of stainless steel 304.

9. The medium-pressure small temperature difference evaporation test circuit device as described in any one of claims 1 to 7, characterized in that, The test prototype is equipped with a scaled-down tube bundle that matches the structure of a pre-designed medium-pressure evaporator. The cavity of the test prototype is equipped with several visualization observation windows, and the visualization observation windows are equipped with visualization observation devices. The hot-side tube side and cold-side shell side inlet and outlet pipelines of the test prototype and the cavity of the test prototype are equipped with monitoring instruments for monitoring at least one of the parameters of temperature, pressure and liquid level. The monitoring instruments and the equipment control signals of the test prototype are all connected to the test loop acquisition system to realize real-time data acquisition, control and storage. The test prototype has tube bundle wall temperature measuring instruments arranged on the outer wall of the heat transfer tubes. The visualization observation device includes a camera, a supplementary light source, a power supply, and an observation terminal. The camera's imaging surface faces the visualization observation window to capture the internal working conditions of the test prototype. The camera's signal output terminal is connected to the observation terminal. The supplementary light source is located on the side of the camera's imaging surface to provide light for the camera's imaging. The supplementary light source's power supply terminal is connected to the power supply. The test loop acquisition system includes the monitoring instrument, the instrument control cabinet, the instrument control acquisition system, and the parameter display terminal connected in sequence. The instrument control acquisition system supports the acquisition of analog and digital signals. The parameter display terminal has a DCS control system and stores the monitoring data obtained by the monitoring instrument to a local server.

10. The medium-pressure small temperature difference evaporation test circuit device as described in claim 9, characterized in that, The process of conducting the test using the medium-pressure, small-temperature-difference evaporation test circuit device is as follows: S1, Pre-test preparation: The steam generator in the hot-side tube circuit is injected with medium to the target liquid level; the cold-side closed circuit in the cold-side shell circuit is injected with medium and vented; the sealing parts of each circuit and the status of the monitoring instruments are checked to ensure that the equipment is normal. S2, Hot-side heating and pressurization: Start the steam generator to heat and pressurize, heat to the first preset temperature, discharge the non-condensable gas in the steam generator, and continue to heat and pressurize the steam generator to the test target condition. The steam generated by the steam generator is regulated by each regulating valve in the hot-side pipe circuit to adjust the hot-side pressure and flow rate to the hot-side operating condition target value. S3, Cold-side heating and pressurization: Start the circulating main pump and electric heater in the cold-side shell-side circuit to heat the cold-side medium to the second preset temperature. Adjust the cold-side circuit pressure to the first preset pressure through the siphon tank in the cold-side shell-side circuit. When the temperature difference and pressure difference between the cold-side closed circuit and the cold-side shell-side of the test prototype are within the preset range, switch the test circuit pipeline to connect the cold-side shell-side circuit with the cold-side shell-side of the test prototype. Continue to heat and pressurize the cold-side shell-side circuit to the target value of the test conditions. During the test, maintain the liquid level of the cold-side shell-side of the test prototype at the target value and keep it stable to ensure the stability of the test conditions. S4, Test Operation: The slightly superheated steam in the hot-side tube circuit is introduced into the hot-side tube of the test prototype to exchange heat with the cold-side shell medium of the test prototype. The hot and cold side parameters are adjusted in real time to keep the superheat of the tube bundle wall of the test prototype stable at ≤4℃, maintain stable operation of the test conditions, and run for no less than the preset time. During the test, at least one parameter among temperature, pressure, flow rate, liquid level and wall temperature of each preset monitoring point is collected in real time, and the evaporation flow pattern change process is captured simultaneously. S5, Test End: In the hot-side tube circuit, gradually reduce the heating power of the steam generator and depressurize the steam generator to achieve temperature and pressure reduction; in the cold-side shell circuit, gradually reduce the heating power of the electric heater; during the test, control the cooling rate of each circuit to ≤50℃ / h and the pressure reduction rate to ≤0.2MPa / min. After the temperature of each circuit drops to the third preset temperature and the pressure drops to atmospheric pressure, safely shut down the test device, and the test ends.

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