Temperature Load Control System and Method for Deep Geotechnical Engineering Disturbance Simulation Facility

Abstract

This invention discloses a temperature load control system and method for a deep geotechnical engineering disturbance simulation facility. The system includes a heat transfer oil unit, a resistance heating unit, and a cooling water unit. The heat transfer oil unit heats the interior of the main cabin using circulating heat transfer oil to achieve temperature rise. The resistance heating unit heats the exterior of the main cabin using resistance heating to achieve preheating, assist in heating the heat transfer oil unit, and maintain continuous temperature. The cooling water unit cools the heat transfer oil in the heat transfer oil unit using circulating cooling water, thereby indirectly cooling the main cabin after the test. This invention fully considers the characteristics of deep geotechnical engineering disturbance simulation facilities and can provide a high-temperature simulation environment for them.

Description

Technical Field

[0001] This invention relates to geotechnical engineering testing, specifically to a temperature load control system and method for a deep geotechnical engineering disturbance simulation facility. Background Technology

[0002] The environment in which deep rock masses exist is characterized by high ground stress, high ground temperature and high karst water pressure. In particular, as the underground depth increases, the high stress field of deep rock masses accumulates, and the ground temperature in some areas can reach as high as 250℃. This makes the implementation of deep geotechnical engineering extremely difficult, and therefore experimental research is required.

[0003] To simulate deep multi-field coupled environments and engineering disturbance conditions, and to accurately observe and control the evolution of discontinuous internal structures and external nonlinear behavior of rock masses, numerous geotechnical engineering disturbance simulation facilities have been developed for experimental research. However, current simulation facilities generally cannot accurately and stably control temperature, especially unable to provide long-term stable high-temperature environments (e.g., maintaining a deep geotechnical environment of 250°C for weeks or even months), which limits more accurate and effective experiments. Summary of the Invention

[0004] The purpose of this invention is to provide a temperature load control system and method for a deep geotechnical engineering disturbance simulation facility. This invention fully considers the characteristics of deep geotechnical engineering disturbance simulation facilities and can provide a high-temperature simulation environment for deep geotechnical engineering disturbance simulation facilities.

[0005] The technical solution adopted in this invention is:

[0006] A temperature load control system for a deep geotechnical engineering disturbance simulation facility includes a heat transfer oil unit, a resistance heating unit, and a cooling water unit. The heat transfer oil unit heats the interior of the main compartment using circulating heat transfer oil, and includes a circulating oil pump, a high-level oil tank supplying oil to the circulating oil pump, and a low-level oil tank storing discharged heat transfer oil for recirculation. The high-level oil tank is replenished by a make-up oil pump. The outlet of the circulating oil pump is sequentially connected to an electric heater, a first switching valve, an oil storage tank, and a second switching valve. The first switching valve switches the flow of heat transfer oil to or around the cooler. The second switching valve switches the flow of heat transfer oil back to the circulating oil pump or to a third switching valve. The third switching valve switches the flow of heat transfer oil from top to bottom or from bottom to top through the interior of the main compartment and out of the cooler. After flowing out of the main compartment, the oil flows back to the circulating oil pump through the gas-liquid separator. Shut-off valves are installed on the external pipes at the upper and lower ends of the main compartment. The external pipe at the lower end of the main compartment is connected to the low-level oil tank through the drain pump. The resistance heating unit is used to heat the outside of the main compartment by resistance heating, thereby achieving preheating, assisting the heating of the heat transfer oil unit, and maintaining continuous heat preservation. It includes an outer shell that can surround and seal the main compartment and resistance heating elements distributed and installed on the inner wall of the outer shell. The cooling water unit is used to cool the heat transfer oil in the heat transfer oil unit with circulating cooling water, thereby indirectly cooling the main compartment after the test. It includes a circulating cooling water pump that can deliver circulating cooling water to the cooler, a cooling water tank for supplying water to the circulating cooling water pump, and a cooling tower for dissipating heat from the circulating cooling water after heat absorption.

[0007] Preferably, the electric heater and the circulating oil pump are interlocked: the electric heater is not powered when the circulating oil pump is not started, the circulating oil pump does not stop working when the electric heater is not powered, and when the circulating oil pump stops working after the electric heater is powered off is manually controlled.

[0008] Preferably, the low-level oil tank is equipped with a cooling coil, and the cooling water unit can also use circulating cooling water to cool the cooling coil, thereby indirectly cooling the heat transfer oil in the low-level oil tank.

[0009] Preferably, two circulating oil pumps are used, one in use and the other as a backup.

[0010] Preferably, the circulating oil pump is a canned pump driven by a constant torque explosion-proof variable frequency motor.

[0011] Preferably, two shut-off valves are provided on each of the external pipes at the upper and lower ends of the main cabin. The shut-off valves are electric high-temperature and ultra-high-pressure gate valves with a diameter of not less than DN65.

[0012] Preferably, the outer shell is divided into two half-shells from the middle. Both half-shells can move to close and separate. The joint of the two half-shells is provided with a sealing groove, and the sealing groove is filled with high-temperature resistant sealing filler. When the two half-shells are closed, they can form a sealed cavity to surround and seal the main compartment. High-temperature resistant furnace lining modules are distributed on the inner wall of the outer shell. After being heated at high temperature, the furnace lining modules expand internally, causing them to press against each other and forming a solidified hard layer on the surface.

[0013] Preferably, the resistance heating element is wound around an insulating ceramic tube, and the insulating ceramic tube is fixed to the inner wall of the outer shell by an insulating ceramic component. The outer shell body is made of stainless steel.

[0014] A method for controlling the temperature load of a deep geotechnical engineering disturbance simulation facility, employing the aforementioned temperature load control system, firstly preheats the main chamber by surrounding and sealing it with resistance heating units; then, heated heat transfer oil is introduced into the main chamber using a heat transfer oil unit, and the oil is circulated between the main chamber and the electric heater via a circulating oil pump, causing the heat transfer oil temperature to continuously rise. With the assistance of the resistance heating units, the main chamber reaches the ambient temperature required for the experiment; finally, the connection between the main chamber and the heat transfer oil unit is disconnected, and the temperature is lowered. The main cabin is pressurized; then it is kept warm for a long time. During this time, the heat transfer oil unit does not work, and the resistance heating unit ensures that the main cabin is always kept at the test temperature. After the test is completed, the resistance heating unit is turned off, the heat transfer oil unit is turned on and the electric heater in it is turned off, and the cooling water unit is turned on. The heat transfer oil unit makes the heat transfer oil circulate in the main cabin and the external pipeline of the main cabin. The cooling water unit makes the circulating cooling water cool the heat transfer oil in the external pipeline of the main cabin, thereby indirectly cooling the main cabin. The circulating cooling water that has absorbed heat dissipates heat through the cooling tower, and finally reduces the temperature of the heat transfer oil and the main cabin to below a certain temperature.

[0015] Preferably, the working process of the heat transfer oil unit includes the following steps:

[0016] S1. Oil Injection: Open the valve on the external oil tank pipeline connecting the replenishment pump, close the valve on the pipeline connecting the low-level oil tank to the replenishment pump, close the valve on the pipeline connecting the external pipeline at the lower end of the main cabin to the drain pump, switch the first switching valve to the heat transfer oil bypass cooler, switch the second switching valve to the heat transfer oil flow to the third switching valve, open the shut-off valve on the external pipeline at the upper and lower ends of the main cabin, start the replenishment pump, and fill the entire heat transfer oil unit with heat transfer oil through the high-level oil tank. When the high-level oil tank has a liquid level display, it means that the entire heat transfer oil unit has been filled. Start the circulating oil pump to fully circulate the heat transfer oil and use the gas-liquid separator to discharge air, in preparation for boiling the oil.

[0017] S2. Heating the main compartment: First, switch the first switching valve to the heat transfer oil bypass cooler, switch the second switching valve to allow the heat transfer oil to flow back to the circulating oil pump, turn on the circulating oil pump and the electric heater, and heat the oil to the target temperature according to the oil boiling process; then open the shut-off valves on the external pipelines at the upper and lower ends of the main compartment, switch the second switching valve to allow the heat transfer oil to flow to the third switching valve, and switch the third switching valve to allow the heat transfer oil to flow from top to bottom through the interior of the main compartment, injecting the heat transfer oil into the main compartment. If the temperature difference between the heat transfer oil at the upper and lower ends of the main compartment exceeds a certain value, switch the third switching valve to allow the heat transfer oil to flow from bottom to top through the interior of the main compartment. By changing the flow direction of the heat transfer oil in the main compartment, the temperature field in the main compartment is made uniform. The temperature of the heat transfer oil is precisely controlled by adjusting the flow rate of the circulating oil pump and the power of the electric heater.

[0018] S3. Cooling the heat transfer oil in the external pipeline of the main compartment: When the temperature of the main compartment reaches the test requirements, the heat transfer oil in the external pipeline of the main compartment needs to be cooled. Cut off the power supply of the electric heater and the shut-off valves on the external pipelines at the upper and lower ends of the main compartment. Switch the second switching valve to allow the heat transfer oil to flow back to the circulating oil pump. The circulating oil pump continues to run to prevent the heat transfer oil in the electric heater from coking. At the same time, switch the first switching valve to allow the heat transfer oil to enter the cooler and turn on the cooling water unit until the heat transfer oil in the external pipeline of the main compartment drops below a certain temperature. Then turn off the circulating oil pump.

[0019] S4. Cooling the Main Cabin: After the main cabin test is completed and the pressure drops to 0MPa, the main cabin needs to be cooled down. Open the shut-off valves on the external pipelines at the upper and lower ends of the main cabin, switch the first switching valve to allow the heat transfer oil to enter the cooler, switch the second switching valve to allow the heat transfer oil to flow to the third switching valve, start the circulating oil pump, turn off the resistance heating unit, and turn on the cooling water unit. This allows the heat transfer oil to circulate in the external and internal pipelines of the main cabin. The circulating cooling water cools the heat transfer oil and indirectly cools the main cabin. Finally, the temperature of the heat transfer oil and the main cabin is reduced to a certain level. Then, the circulating oil pump and the cooling water unit are turned off.

[0020] S5. Oil Discharge: Open the shut-off valve on the external pipeline at the lower end of the main cabin and the valve on the pipeline connecting the external pipeline at the lower end of the main cabin to the oil discharge pump, start the oil discharge pump, and pump the heat transfer oil in the main cabin and the heat transfer oil unit to the low-level oil tank.

[0021] The beneficial effects of this invention are:

[0022] This application fully considers the characteristics of deep geotechnical engineering disturbance simulation facilities. It adopts a heat transfer oil unit to heat the internal components by driving the external circulation of heat transfer oil under low pressure. Once the main chamber and internal specimens reach the test temperature, the connection between them and the heat transfer oil unit can be closed. A resistance heating unit is used to heat the outer surface of the main chamber, which can improve the heating efficiency of the main chamber by preheating and simultaneously heating the internal and external components of the auxiliary heat transfer oil unit. It can also maintain the temperature continuously without requiring the heat transfer oil unit to circulate for a long time, making it easy to control. It can also ensure that the main chamber and internal specimens are heated evenly. The temperature of the heat transfer oil can be precisely controlled by adjusting the flow rate of the circulating oil pump and the power of the electric heater. A cooling water unit is used to cool the heat transfer oil in the heat transfer oil unit with circulating cooling water, thereby indirectly cooling the main chamber, saving oil and water and avoiding environmental pollution. Therefore, this system can provide a stable high-temperature simulation environment for deep geotechnical engineering disturbance simulation facilities. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a system schematic diagram of the heat transfer oil unit in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the resistance heating unit in an embodiment of the present invention.

[0026] Figure 3 This is a system schematic diagram of the cooling water unit in an embodiment of the present invention.

[0027] In the diagram: 1.1b~1.5b, ball valve; 2b, valve; 3b, circulating cooling water pump; 4b, filter; 5b, cooling water tank; 6b, cooling tower; 7b, outer shell; 8b, low-level oil tank; 9.1b~9.4b, ball valve; 10.1b~10.2b, filter; 11b-replenishment pump; 12b-high-level oil tank; 13b-gas-liquid separator; 14b-sampler; 15-main compartment; 16.1b-16.2b, Filter; 17.1b-17.2b, Circulating oil pump; 18.1b-18.5b, Valve; 19b, Electric heater; 20.1b, First switching valve; 20.2b, Second switching valve; 21b, Cooler; 22b, Oil storage tank; 23b, Third switching valve; 24b, Electric valve; 25b, Oil discharge pump; 26.1b-26.4b, Shut-off valve. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0030] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0031] Example 1

[0032] A project requires simulating stress conditions at a depth of 5000m underground by testing large-sized rock samples measuring 800mm x 800mm x 800mm. The main chamber (15) has a total volume of 3.3m³. 3 The maximum working pressure (containing pressure) is 130MPa, and the maximum working temperature is 250℃. It needs to maintain ultra-high pressure and high temperature for 1 month.

[0033] In order to provide a stable high-temperature simulation environment for the aforementioned deep geotechnical engineering disturbance simulation facility, this embodiment provides a temperature load control system for the deep geotechnical engineering disturbance simulation facility, including a heat transfer oil unit, a resistance heating unit, and a cooling water unit; the specific details are as follows.

[0034] I. About the heat transfer oil unit

[0035] The heat transfer oil unit is used to heat the interior of the main cabin 15 with circulating heat transfer oil, thereby raising the temperature. Figure 1As shown, it mainly includes a circulating oil pump (17.1b or 17.2b), a high-level oil tank 12b that supplies oil to the circulating oil pump (17.1b or 17.2b), and a low-level oil tank 8b that stores the discharged heat transfer oil for circulation. The high-level oil tank 12b is replenished by a makeup oil pump 11b. The outlet of the circulating oil pump (17.1b or 17.2b) is sequentially connected to an electric heater 19b, a first switching valve 20.1b, an oil storage tank 22b, and a second switching valve 20.2b. The first switching valve 20.1b can switch the flow of heat transfer oil to or from the cooler 2. 1b, the second switching valve 20.2b can switch the flow of heat transfer oil back to the circulating oil pump (17.1b or 17.2b) or to the third switching valve 23b. The third switching valve 23b can switch the flow of heat transfer oil from top to bottom or from bottom to top through the interior of the main compartment 15 and out of the interior of the main compartment 15 before passing through the gas-liquid separator 13b and flowing back to the circulating oil pump (17.1b or 17.2b). The external pipes at the upper and lower ends of the main compartment 15 are equipped with shut-off valves (26.1b~26.4b). The external pipe at the lower end of the main compartment 15 is connected to the low-level oil tank 8b through the oil discharge pump 25b.

[0036] The preferred heat transfer oil for the heat transfer oil unit is Mobil 605. Mobil 605 is a high-performance heat transfer oil used in closed systems ranging from -12°C to 315°C. It is formulated with highly refined base oils that have resistance to thermal decomposition and chemical oxidation. It has excellent thermal stability, long service life, and lower volatility and toxicity. It is less prone to deposit formation or viscosity increase during use. Furthermore, Mobil 605 has excellent heat transfer efficiency, and its ideal viscosity allows for easy pumping at both start-up and operating temperatures. Its excellent thermal conductivity also helps achieve faster heat dissipation. Additionally, Mobil 605 exhibits good resistance to thermal decomposition at recommended operating temperatures, so its flash point does not decrease significantly under normal use.

[0037] In the heat transfer oil unit, the elevated oil tank 12b plays several important roles besides supplying oil to the circulating oil pumps (17.1b or 17.2b), including: 1) storing the expansion after heating—due to the small diameter of the piping in the liquid phase circulation system, the heat transfer oil undergoes volume changes due to expansion during heating and contraction during cooling. For every 100°C increase in temperature, the volume of the heat transfer oil expands by 10% compared to its room temperature. Therefore, the elevated oil tank 12b can absorb these volume changes; 2) venting and dehydration—the heat transfer oil circulation is powered by the circulating oil pumps (17.1b or 17.2b). To ensure the circulating oil pumps (17.1b or 17.2b) can perform their specified functions, cavitation must be avoided, venting and dehydration are necessary. The elevated oil tank 12b is connected to the inlet of the circulating oil pumps (17.1b and 17.2b) through piping. The heat transfer oil supply pipe is always located below the lowest point, while the return pipe is always located... Placed above the highest point to ensure the entire system is in a self-venting state, the gas in the heat transfer oil flows to the high-level oil tank 12b. Open the vent valve of the high-level oil tank 12b to restore the system to normal pressure. When the pressure in the high-level oil tank 12b exceeds the set value, the safety valve will trip to release pressure; 3) Safety oil replenishment - Due to the leakage of heat transfer oil and the generation of low-boiling substances, the amount of heat transfer oil in the system is insufficient. Appropriate replenishment is required. Cold heat transfer oil must never be directly added to hot heat transfer oil in operation, because if there is water in the heat transfer oil, its volume will expand rapidly after vaporization, the pressure will rise, and the heat transfer oil will be sprayed out. When replenishing oil through the high-level oil tank 12b, the impact on the system is small, and safe oil replenishment can be achieved; 4) When injecting oil, first inject the oil into the high-level oil tank 12b, which will automatically flow into the heat transfer oil unit pipeline, acting as an intermediate tank; 5) In case of power failure, use cold oil to replace the heat medium in the main compartment 15; 6) High-level replenishment pressure head.

[0038] The volume of the high-level oil tank 12b is 1.3 times the volume increased by the expansion of the heat transfer oil in the heat transfer oil unit at the highest operating temperature. Its design pressure is 0.2MPa. The vertical clearance between the bottom of the high-level oil tank 12b and other components of the heat transfer oil unit is 1.5m. It is equipped with a remote pressure sensor and a liquid level sensor.

[0039] like Figure 1 As shown, in this embodiment, preferably, the low-level oil tank 8b is equipped with a cooling coil. The cooling water unit can also use circulating cooling water to cool the cooling coil, thereby indirectly cooling the heat transfer oil in the low-level oil tank 8b. If the heat transfer oil entering the low-level oil tank 8b is higher than 60°C, it needs to be cooled by the cooling coil through the cooling water unit, thereby indirectly cooling the heat transfer oil in the low-level oil tank 8b, quickly reducing the oil temperature to below 60°C to prevent oxidation of the heat transfer oil. A screen filter and a magnetic filter can be installed at the input end of the low-level oil tank 8b. The heat transfer oil is recycled, and filtration facilitates recycling.

[0040] The main functions of the low-level oil tank 8b are: 1) to store the heat transfer oil in the heat transfer oil unit; 2) to receive the heat transfer oil overflowing from the heat transfer oil unit; and 3) to replenish the heat transfer oil required by the heat transfer oil unit under certain circumstances. Furthermore, the vent of the low-level oil tank 8b should be connected to a safe area and should not be equipped with a valve. A firewall should separate the low-level oil tank 8b from the electric heater 19b. The low-level oil tank 8b should be placed at the lowest position in the system. During normal operation, the low-level oil tank 8b should be at a low liquid level, ready to receive external heat transfer oil at any time.

[0041] In this embodiment, preferably, the electric heater 19b and the circulating oil pumps (17.1b and 17.2b) are interlocked: the electric heater 19b is not powered when the circulating oil pumps (17.1b and 17.2b) are not started; the circulating oil pumps (17.1b and 17.2b) do not stop working when the electric heater 19b is not powered; and when the circulating oil pumps (17.1b and 17.2b) stop working after the electric heater 19b is powered off is manually controlled. This can prevent misoperation from causing local overheating, cracking, and coking of the heat transfer oil that has stopped flowing in the electric heater 19b.

[0042] like Figure 1 As shown, in this embodiment, preferably, two circulating oil pumps (17.1b and 17.2b) are used, one in operation and the other as a backup, to improve reliability. The circulating oil pumps (17.1b and 17.2b) are preferably canned motors driven by explosion-proof variable frequency motors with constant torque. In general, ordinary centrifugal pumps with mechanical seals are used. Ordinary centrifugal pumps are driven by connecting the pump impeller shaft to the motor shaft via a coupling, causing the impeller and motor to rotate together. This can lead to leakage under high temperature and pressure. Considering the importance of this project and environmental requirements, this application selects a canned motor to drive the heat transfer oil. A canned motor is a seal-free pump; both the pump and the drive motor are sealed within a pressure vessel filled with the pumped medium. This pressure vessel has only a static seal, and a wiring harness provides the rotating magnetic field to drive the rotor. This structure eliminates the rotating shaft sealing device of traditional centrifugal pumps, thus achieving complete leak-free operation. Simultaneously, for more precise temperature control, more precise adjustment of the heat transfer oil flow rate is required; therefore, this application selects an explosion-proof variable frequency motor for drive.

[0043] In this embodiment, preferably, two electric heaters 19b are used: one with a power of 400kW and the other with a power of 200kW as a backup. The electric heaters 19b are flange-mounted for quick replacement. The electric heater 19b comprises a seamless stainless steel tube, a spiral resistance wire evenly distributed within the seamless stainless steel tube, and high-temperature crystalline magnesium oxide powder filled within the seamless stainless steel tube. The high-temperature crystalline magnesium oxide powder has excellent thermal conductivity and insulation properties. When current flows through the spiral resistance wire, the generated heat is efficiently and evenly diffused through the high-temperature crystalline magnesium oxide powder to the surface of the seamless stainless steel tube, and then efficiently and evenly transferred to the heat transfer oil, achieving the heating purpose. This structure has an extremely long service life and is easy to maintain.

[0044] In this embodiment, preferably: Figure 1 As shown, two shut-off valves are installed on the external pipelines at the upper and lower ends of the main compartment 15. These shut-off valves (26.1b~26.4b) are electrically operated high-temperature and ultra-high-pressure gate valves with a diameter of not less than DN65. The final operating parameters of the main compartment 15 can reach 100MPa and 250℃, while the heat transfer oil unit can only operate at 1MPa and 200℃. Therefore, the pipeline connection needs to be cut off after the temperature of the main compartment 15 and the test piece reaches 200℃. Using two electrically operated high-temperature and ultra-high-pressure gate valves for this purpose reliably cuts off the connection between the main compartment 15 and the heat transfer oil unit. Simultaneously, since the heat transfer oil unit requires a large flow of heat transfer oil to circulate between the main compartment 15 and the electric heater 19b during operation, the shut-off valve diameter is not less than DN65. The first switching valve 20.1b and the second switching valve 20.2b can be electrically operated three-way ball valves, and the third switching valve 23b can be an electrically operated four-way ball valve.

[0045] II. About the resistance heating unit

[0046] The resistance heating unit is used to heat the exterior of the main cabin 15 using resistance heating, thereby achieving preheating, assisting the heat transfer oil unit in heating and maintaining continuous temperature, such as... Figure 2 As shown, it includes an outer shell 7b that can surround and enclose the main cabin 15 and resistance heating elements (not shown in the figure) distributed and installed on the inner wall of the outer shell 7b.

[0047] In this embodiment, preferably: Figure 2As shown, the outer shell 7b is divided into two half-shells from the middle. Both half-shells can move to close and separate. Sealing grooves are provided at the joints of the two half-shells, and high-temperature resistant sealing fillers are placed inside the sealing grooves. The sealing fillers can be soft, high-temperature resistant fiber packing with built-in metal wires. When the two half-shells are closed, they form a sealed cavity that surrounds and seals the main compartment 15. High-temperature resistant furnace lining modules are distributed on the inner wall of the outer shell 7b. When heated to high temperatures, the furnace lining modules expand internally, causing them to press together and forming a hardened layer on the surface. During high-temperature use, the furnace lining modules are pressed together due to expansion, preventing gaps from forming even after prolonged high-temperature use. The hardened layer formed on the surface after high-temperature use has good strength, erosion resistance, and a long service life. Refractory fiber modules can be used, which expand internally and form a hardened layer on the surface when heated to 160℃. The resistance heating element can be wound around an insulating ceramic tube, which can be fixed to the inner wall of the outer shell by insulating ceramic parts. The main body of the outer shell can be made of stainless steel, which is temperature resistant, corrosion resistant, and has a long service life.

[0048] III. About the Cooling Water Unit

[0049] The cooling water unit is used to cool the heat transfer oil in the heat transfer oil unit with circulating cooling water, thereby indirectly cooling the main cabin 15 after the test. Figure 3 As shown, it mainly includes a circulating cooling water pump 3b that can supply circulating cooling water to the cooler 21b, a cooling water tank 5b for supplying water to the circulating cooling water pump 3b, and a cooling tower 6b for dissipating heat from the circulating cooling water after heat absorption; its pipeline is also equipped with some air circuit components, such as ball valves (1.1b~1.5b), valves 2b, and filters 4b.

[0050] This application fully considers the characteristics of deep geotechnical engineering disturbance simulation facilities, and the overall temperature control scheme is as follows:

[0051] Since the test specimen and other components occupy most of the interior space of the main compartment 15, it is impossible to install heating elements inside the main compartment 15. Therefore, a heat transfer oil unit is used to heat the interior by driving the external circulation of heat transfer oil at low pressure. Once the main compartment 15 and the internal test specimen reach the test temperature, the connection between them and the heat transfer oil unit can be closed.

[0052] Furthermore, the main cabin 15 has a wall thickness of 300mm. Although the heat transfer efficiency is low, it will still generate a large thermal stress during the heating process. Therefore, the use of resistance heating units to heat its outer surface can improve the heating efficiency of the main cabin by preheating and simultaneously heating the inside and outside of the auxiliary heat transfer oil unit. The key is that it can also maintain the temperature continuously, without having to circulate the heat transfer oil unit for a long time. It is easy to control and can also ensure that the main cabin 15 and the internal test pieces are heated evenly.

[0053] Furthermore, the temperature of the heat transfer oil can be precisely controlled by adjusting the flow rate of the circulating oil pump (17.1b or 17.2b) and the power of the electric heater 19b;

[0054] Furthermore, for the cooling of the main cabin 15, since the heat transfer oil itself dissipates heat slowly, a cooling water unit is used to cool the heat transfer oil in the heat transfer oil unit with circulating cooling water, thereby indirectly cooling the main cabin 15. After the cooling water and the heat transfer oil exchange heat, they enter the cooling tower 6b to dissipate the heat in the water into the atmosphere, and then flow back to the cooling water tank 5b by the weight of the water, saving oil and water and not polluting the environment.

[0055] Therefore, this system can provide a stable high-temperature simulation environment for deep geotechnical engineering disturbance simulation facilities.

[0056] Example 2

[0057] This embodiment discloses a temperature load control method for a deep geotechnical engineering disturbance simulation facility. The basic method of the aforementioned temperature load control system for a deep geotechnical engineering disturbance simulation facility is as follows:

[0058] First, the main cabin 15 is enclosed by a resistance heating unit and the exterior of the main cabin 15 is heated by resistance heating to achieve preheating.

[0059] Then, heated heat transfer oil is introduced into the main compartment 15 using the heat transfer oil unit. The heat transfer oil is circulated between the main compartment 15 and the electric heater 19b by the circulating oil pump (17.1b or 17.2b), so that the temperature of the heat transfer oil continues to rise. With the assistance of the resistance heating unit, the main compartment 15 reaches the ambient temperature required for the test.

[0060] Then disconnect the main cabin 15 from the heat transfer oil unit and pressurize the main cabin;

[0061] Then, a long-term heat preservation process is carried out (up to one month). During this period, the heat transfer oil unit does not work, and the resistance heating unit ensures that the main cabin 15 is always maintained at the test temperature.

[0062] After the test is completed, the resistance heating unit is turned off, the heat transfer oil unit is turned on and the electric heater 19b therein is turned off, and the cooling water unit is turned on. The heat transfer oil unit causes the heat transfer oil to circulate in the main compartment 15 and the external pipeline of the main compartment 15. The cooling water unit causes the circulating cooling water to cool the heat transfer oil in the external pipeline of the main compartment 15, thereby indirectly cooling the main compartment 15. The circulating cooling water, after absorbing heat, dissipates heat through the cooling tower 6b, and finally reduces the temperature of the heat transfer oil and the main compartment 15 to below a certain temperature.

[0063] Among them, the heat transfer oil unit is more complex than the resistance heating unit, and the operation steps are more numerous. Its workflow needs to be carefully designed. The workflow of the heat transfer oil unit includes the following steps:

[0064] S1. Oil Injection: Open ball valve 9.2b on the external oil tank pipeline connecting to replenishment pump 11b; close ball valve 9.1b on the pipeline connecting low-level oil tank 8b to replenishment pump 11b; close valve 18.3b on the pipeline connecting the second switching valve 20.2b and the third switching valve 23b to gas-liquid separator 13b; close electric valve 24b on the pipeline connecting the lower external pipeline of main compartment 15 to drain pump 25b; switch the first switching valve 20.1b to the heat transfer oil bypass cooler 21b; and switch the second switching valve 20.2b... Switch to the third switching valve 24b for the heat transfer oil flow, open the shut-off valves (26.1b~26.4b) on the external pipelines at the upper and lower ends of the main compartment 15, start the oil replenishment pump 11b, and fill the entire heat transfer oil unit with heat transfer oil through the high-level oil tank 12b. When the high-level oil tank 12b shows a liquid level, it means that the entire heat transfer oil unit has been filled. Start the circulating oil pump 17b to fully circulate the heat transfer oil and use the gas-liquid separator 13b to discharge air, in preparation for boiling the oil. Under the action of the heat transfer oil's own weight, the entire heat transfer oil pipeline and the main compartment 15 can be filled within 1 hour.

[0065] S2. Heating the Main Cabin: First, switch the first switching valve 20.1b to the heat transfer oil bypass cooler 21b, then switch the second switching valve 20.2b to return the heat transfer oil to the circulating oil pump 17b. Turn on the circulating oil pump 17b and the electric heater 19b. Close the valve 18.3b on the pipe connecting the second switching valve 20.2b and the third switching valve 23b to the gas-liquid separator 13b. Heat the oil to the target temperature according to the oil heating process. Then, open the shut-off valves (26.1b~26.4b) on the external pipes at the upper and lower ends of the main cabin 15 to heat the oil. The second switching valve 20.2b is switched to direct the heat transfer oil flow to the third switching valve 24b, and the third switching valve 23b is switched to allow the heat transfer oil to flow from top to bottom through the main compartment, injecting the heat transfer oil into the main compartment 15. If the temperature difference between the upper and lower ends of the heat transfer oil in the main compartment 15 exceeds a certain value (e.g., 10°C), the third switching valve 23b is switched to allow the heat transfer oil to flow from bottom to top through the main compartment 15. By changing the flow direction of the heat transfer oil in the main compartment 15, the temperature field in the main compartment 15 is made uniform. The temperature of the heat transfer oil is precisely controlled by adjusting the flow rate of the circulating oil pump 17b and the power of the electric heater 19b.

[0066] S3. Cooling the heat transfer oil in the external pipeline of the main compartment 15: When the temperature of the main compartment 15 reaches the test requirements, the heat transfer oil in the external pipeline of the main compartment 15 needs to be cooled. Cut off the power supply of the electric heater 19b and the shut-off valves (26.1b~26.4b) on the external pipelines at the upper and lower ends of the main compartment 15. Switch the second switching valve 20.2b to return the heat transfer oil to the circulating oil pump 17b. The circulating oil pump 17b continues to run to prevent the heat transfer oil in the electric heater 19b from coking. At the same time, switch the first switching valve 20.1b to allow the heat transfer oil to enter the cooler 21b and turn on the cooling water unit until the heat transfer oil in the external pipeline of the main compartment 15 drops to a certain temperature (e.g., 80°C) or below. Then turn off the circulating oil pump 17b.

[0067] S4. Cooling Main Cabin 15: After the test of the main cabin 15 is completed and the pressure drops to 0MPa, the main cabin 15 needs to be cooled down. Open the shut-off valves (26.1b~26.4b) on the external pipes at the upper and lower ends of the main cabin 15, switch the first switching valve 20.1b to allow the heat transfer oil to enter the cooler 21b, switch the second switching valve 20.2b to allow the heat transfer oil to flow to the third switching valve 24b, start the circulating oil pump 17b, turn off the resistance heating unit 19b, and turn on the cooling water unit. This allows the heat transfer oil to circulate in the external pipes and internal pipes of the main cabin 15. The circulating cooling water cools the heat transfer oil and indirectly cools the main cabin 15. Finally, the temperature of the heat transfer oil and the main cabin 15 is reduced to a certain temperature (e.g., 80℃). Finally, turn off the circulating oil pump 17b and the cooling water unit.

[0068] S5. Oil Discharge: Open the shut-off valves (26.3b, 26.4b) on the external pipeline at the lower end of the main compartment 15, and the electric valves 24b and 9.4b on the pipeline connecting the external pipeline at the lower end of the main compartment 15 to the oil discharge pump 25b. Start the oil discharge pump 22b to pump the heat transfer oil in the main compartment 15 and the heat transfer oil unit into the low-level oil tank 8b. The time for draining the heat transfer oil in the main compartment 15 into the low-level oil tank 8b shall not exceed 30 minutes.

[0069] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A temperature load control system for a deep geotechnical engineering disturbance simulation facility, characterized in that: It includes a heat transfer oil unit, a resistance heating unit, and a cooling water unit. The heat transfer oil unit is used to heat the interior of the main compartment with circulating heat transfer oil to achieve temperature rise. It includes a circulating oil pump, a high-level oil tank that supplies oil to the circulating oil pump, and a low-level oil tank that stores the discharged heat transfer oil for circulation. The high-level oil tank is replenished by a make-up oil pump. The outlet of the circulating oil pump is connected in sequence to an electric heater, a first switching valve, an oil storage tank, and a second switching valve. The first switching valve can switch the flow of heat transfer oil to or around the cooler. The second switching valve can switch the flow of heat transfer oil back to the circulating oil pump or to a third switching valve. The third switching valve can switch the flow of heat transfer oil from top to bottom or from bottom to top through the interior of the main compartment and out of the main compartment after passing through the gas-liquid system. The separator returns the oil to the circulating oil pump. Shut-off valves are installed on the external pipes at both the upper and lower ends of the main compartment. The external pipe at the lower end of the main compartment is connected to the low-level oil tank via a drain pump. The resistance heating unit is used to heat the exterior of the main compartment using resistance heating, thereby achieving preheating, assisting in heating the heat transfer oil unit, and maintaining continuous heat preservation. It includes an outer shell that can surround and enclose the main compartment and resistance heating elements distributed and installed on the inner wall of the outer shell. The cooling water unit is used to cool the heat transfer oil in the heat transfer oil unit with circulating cooling water, thereby indirectly cooling the main compartment after the test. It includes a circulating cooling water pump that can supply circulating cooling water to the cooler, a cooling water tank for supplying water to the circulating cooling water pump, and a cooling tower for dissipating heat from the circulating cooling water after heat absorption. The working process of the heat transfer oil unit includes the following steps: S1. Oil Injection: Open the valve on the external oil tank pipeline connecting the replenishment pump, close the valve on the pipeline connecting the low-level oil tank to the replenishment pump, close the valve on the pipeline connecting the external pipeline at the lower end of the main cabin to the drain pump, switch the first switching valve to the heat transfer oil bypass cooler, switch the second switching valve to the heat transfer oil flow to the third switching valve, open the shut-off valve on the external pipeline at the upper and lower ends of the main cabin, start the replenishment pump, and fill the entire heat transfer oil unit with heat transfer oil through the high-level oil tank. When the high-level oil tank has a liquid level display, it means that the entire heat transfer oil unit has been filled. Start the circulating oil pump to fully circulate the heat transfer oil and use the gas-liquid separator to discharge air, in preparation for boiling the oil. S2. Heating the main compartment: First, switch the first switching valve to the heat transfer oil bypass cooler, switch the second switching valve to allow the heat transfer oil to flow back to the circulating oil pump, turn on the circulating oil pump, turn on the electric heater, and heat the oil to the target temperature according to the oil boiling process. Then open the shut-off valves on the external pipelines at the upper and lower ends of the main compartment, switch the second switching valve to the flow of heat transfer oil to the third switching valve, switch the third switching valve to the flow of heat transfer oil from top to bottom through the interior of the main compartment, and inject the heat transfer oil into the main compartment. If the temperature difference of the heat transfer oil at the upper and lower ends of the main compartment exceeds a certain value, switch the third switching valve to the flow of heat transfer oil from bottom to top through the interior of the main compartment. By changing the flow direction of the heat transfer oil in the main compartment, the temperature field in the main compartment is made uniform. The temperature of the heat transfer oil is precisely controlled by adjusting the flow rate of the circulating oil pump and the power of the electric heater. S3. Cooling the heat transfer oil in the external pipeline of the main compartment: When the temperature of the main compartment reaches the test requirements, the heat transfer oil in the external pipeline of the main compartment needs to be cooled. Cut off the power supply of the electric heater and the shut-off valves on the external pipelines at the upper and lower ends of the main compartment. Switch the second switching valve to allow the heat transfer oil to flow back to the circulating oil pump. The circulating oil pump continues to run to prevent the heat transfer oil in the electric heater from coking. At the same time, switch the first switching valve to allow the heat transfer oil to enter the cooler and turn on the cooling water unit until the heat transfer oil in the external pipeline of the main compartment drops below a certain temperature. Then turn off the circulating oil pump. S4. Cooling the Main Cabin: After the main cabin test is completed and the pressure drops to 0MPa, the main cabin needs to be cooled down. Open the shut-off valves on the external pipelines at the upper and lower ends of the main cabin, switch the first switching valve to allow the heat transfer oil to enter the cooler, switch the second switching valve to allow the heat transfer oil to flow to the third switching valve, start the circulating oil pump, turn off the resistance heating unit, and turn on the cooling water unit. This allows the heat transfer oil to circulate in the external and internal pipelines of the main cabin. The circulating cooling water cools the heat transfer oil and indirectly cools the main cabin. Finally, the temperature of the heat transfer oil and the main cabin is reduced to a certain level. Then, the circulating oil pump and the cooling water unit are turned off. S5. Oil Discharge: Open the shut-off valve on the external pipeline at the lower end of the main cabin and the valve on the pipeline connecting the external pipeline at the lower end of the main cabin to the oil discharge pump, start the oil discharge pump, and pump the heat transfer oil in the main cabin and the heat transfer oil unit to the low-level oil tank.

2. The temperature load control system for the deep geotechnical engineering disturbance simulation facility as described in claim 1, characterized in that, The electric heater and the circulating oil pump are interlocked: the electric heater is not powered when the circulating oil pump is not started, the circulating oil pump does not stop working when the electric heater is not powered, and when the circulating oil pump stops working after the electric heater is powered off is manually controlled.

3. The temperature load control system for the deep geotechnical engineering disturbance simulation facility as described in claim 1, characterized in that: The low-level oil tank is equipped with a cooling coil, and the cooling water unit can also use circulating cooling water to cool the cooling coil, thereby indirectly cooling the heat transfer oil in the low-level oil tank.

4. The temperature load control system for the deep geotechnical engineering disturbance simulation facility as described in claim 1, characterized in that: Two circulating oil pumps are used, one in operation and the other as a backup.

5. The temperature load control system for the deep geotechnical engineering disturbance simulation facility as described in claim 1 or 4, characterized in that: The circulating oil pump is a canned pump driven by a constant torque explosion-proof variable frequency motor.

6. The temperature load control system for the deep geotechnical engineering disturbance simulation facility as described in claim 1, characterized in that: Two shut-off valves are installed on each of the external pipes at the upper and lower ends of the main cabin. The shut-off valves are electric high-temperature and ultra-high-pressure gate valves with a diameter of not less than DN65.

7. The temperature load control system for the deep geotechnical engineering disturbance simulation facility as described in claim 1, characterized in that: The outer shell is divided into two half-shells in the middle. Both half-shells can move to close and separate. The joint of the two half-shells is equipped with a sealing groove, which contains high-temperature resistant sealing filler. When the two half-shells are closed, they can form a sealed cavity to surround and seal the main compartment. High-temperature resistant furnace lining modules are distributed on the inner wall of the outer shell. When the furnace lining modules are heated at high temperature, they expand internally, causing them to press against each other and form a solidified hard layer on the surface.

8. The temperature load control system for the deep geotechnical engineering disturbance simulation facility as described in claim 1, characterized in that: The resistance heating element is wound around an insulating ceramic tube, which is fixed to the inner wall of the outer shell by insulating ceramic parts. The main body of the outer shell is made of stainless steel.

9. A method for controlling the temperature load of a deep geotechnical engineering disturbance simulation facility, characterized in that, The temperature load control system of the deep geotechnical engineering disturbance simulation facility as described in any one of claims 1 to 8 is adopted: First, the main chamber is surrounded and sealed by a resistance heating unit, and the exterior of the main chamber is heated by resistance heating to achieve preheating; then, the heated heat transfer oil is input into the main chamber by a heat transfer oil unit, and the heat transfer oil is circulated between the main chamber and the electric heater by a circulating oil pump, so that the temperature of the heat transfer oil continues to rise, and with the assistance of the resistance heating unit, the main chamber reaches the ambient temperature required for the test; Then, the connection between the main cabin and the heat transfer oil unit is disconnected, and the main cabin is pressurized. Then, a long-term heat preservation is carried out. During this time, the heat transfer oil unit does not work, and the resistance heating unit ensures that the main cabin is always maintained at the test temperature. After the test is completed, the resistance heating unit is turned off, the heat transfer oil unit is turned on and the electric heater in it is turned off, and the cooling water unit is turned on. The heat transfer oil unit makes the heat transfer oil circulate in the main cabin and the external pipeline of the main cabin. The cooling water unit makes the circulating cooling water cool the heat transfer oil in the external pipeline of the main cabin, thereby indirectly cooling the main cabin. The circulating cooling water that has absorbed heat dissipates heat through the cooling tower, and finally reduces the temperature of the heat transfer oil and the main cabin to below a certain temperature.

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