Conduction oil system and start-up method using same

Abstract

The invention provides a heat conduction oil system and a start-up method using the same. The heat conduction oil system comprises a high-position expansion tank; an inlet of the oil-gas separator is selectively communicated with an oil outlet of the high-position expansion tank; an inlet of the heater is communicated with an oil outlet of the oil-gas separator through a first pipeline; the circulating pump is arranged on the first pipeline and selectively communicates with the heater and the oil-gas separator; a user to be subjected to heat tracing or heating is included, an inlet of the user to be subjected to heat tracing or heating is selectively communicated to an outlet of the heater through a second pipeline, and an oil outlet of the user to be subjected to heat tracing or heating is selectively communicated to an inlet of the oil-gas separator through a third pipeline; and the outlet of the heater is selectively communicated to the first pipeline at the inlet end of the circulating pump through a fourth pipeline, so that the problems of low temperature, high density, small size and insufficient circulation quantity of the conduction oil in the initial stage of starting are effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical fields of chemical industry, coal chemical industry and direct coal liquefaction, and particularly relates to a heat transfer oil system and a start-up method using the same. Background Art

[0002] The thermal oil system is a heating device that uses thermal oil as the working medium. It is mainly composed of heat source, heat carrier, heating and heat transfer device. Thermal oil is a special industrial heat carrier with good heat transfer performance and chemical stability, and can withstand high temperature and high pressure. The thermal oil system heats up the thermal oil through the heater, and then the hot oil transfers the heat to the heated object through the heat transfer device to achieve the purpose of heating and heat transfer. This system is widely used in industrial fields such as petroleum, chemical, light industry, food, pharmaceutical, textile, papermaking, plastic, building materials, wood, as well as heating and air conditioning in civil buildings. The advantages of the thermal oil system are stability and reliability, high heat transfer efficiency, long service life, low energy consumption, simple operation, etc., so it is favored by the industry and the market.

[0003] However, in the heat transfer oil system, when the circulation is started, due to the low temperature, high density, small volume and insufficient circulation volume of the heat transfer oil, the circulation pump is often emptied and the heat transfer oil system cannot operate normally.

[0004] Therefore, it is necessary to design a heat transfer oil system and a start-up method using the system to eliminate or reduce the phenomenon of circulating pump evacuation and ensure the normal operation of the heat transfer oil system. Summary of the invention

[0005] In view of some or all of the above technical problems existing in the prior art, the present invention proposes a heat transfer oil system and a start-up method using the heat transfer oil system, which can effectively ensure the normal operation of the system.

[0006] According to one aspect of the present invention, a thermal oil system is provided, comprising:

[0007] A high-position expansion tank, the high-position expansion tank is used to store heat transfer oil,

[0008] An oil-gas separator, the inlet of which is selectively connected to the oil outlet of the high-position expansion tank,

[0009] a heater, wherein the inlet of the heater is connected to the oil outlet of the oil-gas separator through a first pipeline,

[0010] A circulation pump is disposed on the first pipeline and selectively communicated with the heater and the oil-gas separator.

[0011] The inlet of the user to be heated or heated is selectively connected to the outlet of the heater through a second pipeline, and the oil outlet of the user to be heated or heated is selectively connected to the inlet of the oil-gas separator through a third pipeline.

[0012] The outlet of the heater is selectively connected to the first pipeline at the inlet end of the circulation pump through a fourth pipeline.

[0013] In one embodiment, a user branch line is selectively connected between the second pipeline and the third pipeline, the user branch line is connected in parallel with the user to be heated or heated, and a pressure regulating valve is provided on the user branch line.

[0014] In one embodiment, the third pipeline is selectively connected to the inlet of the high-level expansion tank through a pump inlet degassing line.

[0015] In one embodiment, the first pipeline at the outlet end of the circulation pump is selectively connected to the inlet of the high-level expansion tank through a pump outlet degassing line.

[0016] In one embodiment, the gas outlet of the high-level expansion tank is connected to the inlet of the oil-gas cooler, the outlet of the oil-gas cooler is connected to the inlet of the low-level oil storage tank, and the outlet of the low-level oil storage tank is connected to the inlet of the high-level expansion tank through an oil injection pump.

[0017] In one embodiment, the degassing port of the user to be heated or heated is selectively connected to the inlet of the oil-gas cooler through a user degassing line.

[0018] In one embodiment, an unexpected branch is selectively provided between the third pipeline and the inlet of the low-level oil storage tank.

[0019] In one embodiment, the gas outlet of the oil-gas separator is connected to the inlet of the high-level expansion tank.

[0020] According to another aspect of the present invention, there is provided a method for starting up a thermal oil system using the above-mentioned thermal oil system, comprising:

[0021] Step 1: The heat transfer oil circulates in the heat transfer oil system and is initially heated.

[0022] Step 2: The heat transfer oil is heated to the dehydration temperature and the dehydration operation is performed.

[0023] Step 3: The heat transfer oil is heated to the degassing temperature and degassing is performed.

[0024] Step 4: Heat the heat transfer oil to the start-up temperature.

[0025] In one embodiment, step one includes:

[0026] In the first sub-step, the heat transfer oil is sent from the high-position expansion tank through the oil-gas separator to the heater by the circulation pump for heating, and the heated heat transfer oil is sent back to the inlet of the circulation pump by the fourth pipeline for circulation.

[0027] The second sub-step is to reduce the amount of the heat transfer oil heated by the heater and returned to the inlet of the circulation pump, and to make the second pipeline and the third pipeline connected through the user branch line, and the heated heat transfer oil is sequentially returned to the oil-gas separator through the second pipeline, the user branch line and the third pipeline for circulation.

[0028] The third sub-step is to connect the second pipeline with the third pipeline through the user to be heated or heated, and the heated heat transfer oil passes through the second pipeline, the user to be heated or heated, and the third pipeline in sequence and returns to the oil-gas separator for circulation.

[0029] Compared with the prior art, the advantages of the present invention are: in the heat transfer system, the heat transfer oil heated by the heater can be sent back to the inlet of the circulation pump through the fourth pipeline to establish a circulation, effectively solving the problems of low temperature, high density, small volume and insufficient circulation volume of the heat transfer oil in the initial stage of operation, avoiding the circulation pump from being emptied, and ensuring the normal operation of the heat transfer oil system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0031] Figure 1 A thermal oil system according to an embodiment of the present invention is shown.

[0032] The drawings are not drawn to scale. DETAILED DESCRIPTION

[0033] In order to make the technical solutions and advantages of the present invention more clearly understood, the exemplary embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than an exhaustive list of all the embodiments. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0034] The embodiment of the present invention provides a heat transfer oil system. Figure 1As shown, the thermal oil system includes a high-level expansion tank 1, an oil-gas separator 3, a heater 5, a circulation pump 4 and a user to be heated or heated. The high-level expansion tank 1 is used to store thermal oil, to maintain a certain liquid level during the operation of the thermal oil system, and to further provide the circulation pump 4 with an inlet oil pressure and a medium. Of course, the oil and gas generated by the thermal oil system can also be discharged into the high-level expansion tank 1 for receiving oil and gas. The inlet of the oil-gas separator 3 is selectively connected to the oil outlet of the high-level expansion tank 1 to receive the thermal oil and separate the oil and gas of the thermal oil to avoid or reduce excessive gas from entering the downstream circulation pump 4. It is easy to understand that the selective connection in this application mainly refers to the provision of a regulating valve on the pipeline connecting the two connected components, such as the oil-gas separator 3 and the high-level expansion tank 1, to shut off, adjust the flow size or open the connection between the two. The inlet of the heater 5 is connected to the oil outlet of the oil-gas separator 3 through the first pipeline 19. The heater 5 acts as a heat source to heat the thermal oil. The circulation pump 4 is arranged on the first pipeline 19 to pump the heat transfer oil from the oil-gas separator 3 into the heater 5. It is easy to understand that the circulation pump 4 is selectively connected with the heater 5 and the oil-gas separator 3, that is, regulating valves are arranged on the first pipeline 19, between the circulation pump 4 and the heater 5, and between the circulation pump 4 and the oil-gas separator 3. The inlet of the user to be heated or heated is selectively connected to the outlet of the heater 5 through the second pipeline 20. The oil outlet of the user to be heated or heated is selectively connected to the inlet of the oil-gas separator 3 through the third pipeline 21. It can be seen that the heated heat transfer oil can enter the user to be heated or heated through the second pipeline 20 for heat transfer, and then flow back to the oil-gas separator 3 through the third pipeline 21, and then be sent to the heater 5 through the circulation pump 4 for heating, forming a cycle in which the heat transfer oil is heated and heated, and heat is exchanged with the user to be heated or heated. According to the present application, the outlet of the heater 5 is selectively connected to the first pipeline 19 at the inlet end of the circulation pump 4 through the fourth pipeline 11.

[0035] In the initial stage of operation, the heat transfer oil has low temperature, high density, small volume and insufficient circulation volume. The above arrangement allows the heated heat transfer oil to be transported back to the inlet of the circulation pump 4 through the fourth pipeline 11, and then sent to the heater 5 by the circulation pump 4, which can effectively avoid the problem of the circulation pump 4 being emptied and the heat transfer oil system being unable to operate normally.

[0036] A user branch line 17 is selectively connected between the second pipeline 20 and the third pipeline 21. The user branch line 17 is connected in parallel with the user to be heated or heated. In the state where the heat transfer oil is initially heated, the heat transfer oil can be circulated through the user branch line 17. At this time, the user to be heated or heated is not connected to the heater 5. That is, through the circulation between the user branch line 17 and the second pipeline 20 and the third pipeline 21, the second pipeline 20 and the third pipeline 21 can be filled with heat transfer oil to discharge the air in the corresponding pipelines. In addition, a pressure regulating valve 18 is provided on the user branch line 17 to control the pressure of the heat transfer oil in the second pipeline 20 and the third pipeline 21 during the start-up process.

[0037] The third pipeline 21 is selectively connected to the inlet of the high-level expansion tank 1 through the pump inlet degassing line 12. That is, the high-level expansion tank 1 and the oil-gas separator 3 are arranged in parallel at the downstream end of the third pipeline 21. When the pump inlet degassing line 12 and the third pipeline 21 are fully opened, part of the heat transfer oil returning to the third pipeline 21 enters the oil-gas separator 3, and part enters the high-level expansion tank 1. It can be seen that the pump inlet degassing line 12 transports part of the gas back to the high-level expansion tank 1, plays a degassing role, and ensures the normal operation of the heat transfer oil system.

[0038] The first pipeline 19 at the outlet end of the circulation pump 4 is selectively connected to the inlet of the high-position expansion tank 1 through the pump outlet end degassing line 13. The pump outlet end degassing line 13 transports the gas passing through the circulation pump 4 back to the high-position expansion tank 1, plays a degassing role, and prevents excessive gas from entering the heater 5.

[0039] The gas outlet of the high-level expansion tank 1 is connected to the inlet of the oil-gas cooler 6. The outlet of the oil-gas cooler 6 is connected to the inlet of the low-level oil storage tank 2. The outlet of the low-level oil storage tank 2 is connected to the inlet of the high-level expansion tank 1 through the oil injection pump 7. A pressure control system and a safety valve are provided in the high-level expansion tank 1, and the pressure exceeding the set pressure will be discharged through the self-operated pressure regulating valve. The discharged oil and gas enter the oil-gas cooler 6 for cooling, and the cooled heat transfer oil is transported and stored in the low-level oil storage tank 2. The low-level oil storage tank 2 can replenish the heat transfer oil for the high-level expansion tank 1 to ensure the liquid level of the high-level expansion tank 1.

[0040] The degassing port of the user to be heated or heated is selectively connected to the inlet of the oil-gas cooler 6 through the user degassing line. In the present application, three users to be heated or heated are drawn and numbered 8, 9, and 10 respectively. It is easy to understand that according to the needs of the project, the number of users to be heated or heated can be one or more. For example, the user to be heated or heated can be one or more of the equipment, pipeline jackets or users to be heated. In the case where there are multiple users to be heated or heated, these users to be heated or heated are arranged in parallel between the second pipeline 20 and the third pipeline 21. These users to be heated or heated 8, 9, and 10 are connected to the inlet of the oil-gas cooler 6 through their respective user degassing lines 14, 15, and 16. It is easy to understand that in order to achieve selective connection, regulating valves are arranged on the user degassing lines 14, 15, and 16.

[0041] The gas outlet of the oil-gas separator 3 is connected to the inlet of the high-position expansion tank 1. In other words, the gas separated by the oil-gas separator 3 can be returned to the high-position expansion tank 1.

[0042] An accidental branch 22 is selectively connected between the third pipeline 21 and the inlet of the low-level oil storage tank 2. Thus, at the downstream end of the third pipeline 21, there are three branch pipelines, namely, the oil-gas separator 3, the high-level expansion tank 1 and the low-level oil storage tank 2, to meet the requirements of different working conditions. During shutdown or failure of the heat transfer oil system, the connection between the third pipeline 21 and the high-level expansion tank 1 and the oil-gas separator 3 can be shut off, so that the heat transfer oil can flow back to the low-level oil storage tank 2 through the accidental branch 22.

[0043] In the present application, the heater 5 can be an electric heater and can automatically adjust the heating according to the temperature required by the user. The oil-gas cooler 6 can be cooled by circulating water or other cooling methods. The high-level expansion tank 1 is selectively connected to an external nitrogen, for example, to adjust the pressure of the heat transfer oil in the high-level expansion tank 1.

[0044] According to the following Figure 1 Describe in detail the start-up method using a thermal oil system.

[0045] Step 1: The heat transfer oil circulates in the heat transfer system and is initially heated up.

[0046] More specifically, the first sub-step is performed first. At room temperature, the oil injection pump 7 is used to inject the heat transfer oil in the low-level oil storage tank 2 (in the oil barrel or oil tanker used for the first start of work) into the high-level expansion tank 1. A small cycle is established from the high-level expansion tank 1 to the circulation pump 4 to the heater 5, and then through the outlet of the heater 5 to the fourth pipeline 11 and back to the inlet of the circulation pump 4. It is easy to understand that during this small cycle, the heater 5 is not connected to the user to be heated or heated and the user branch line. After the preset temperature of the heater 5 is given (depending on the actual situation, the preset temperature is not the same, for example, in one embodiment, it is 110°C), the heater 5 works and enters the automatic heating mode. The heater 5 can gradually heat up to the preset temperature according to the set heating mode.

[0047] Then, the second sub-step is carried out. As the amount of thermal oil in the thermal oil system increases and the temperature rises, the volume of the thermal oil will increase. At this time, the regulating valve on the fourth pipeline 11 is gradually closed to transport the thermal oil to the second pipeline 20, and to the third pipeline 21 through the user branch line 17, and then return to the oil-gas separator 3. That is, after the thermal oil is heated, a circulation is established through the user branch line 17. It is easy to understand that in this cycle, the heater 5 is not yet connected to the user to be heated or heated. In this process, it is necessary to control the liquid level of the high-level expansion tank 1 at 5%-70%, and the thermal oil pump flow rate of the circulating pump 4 is not less than 50m 3 / h, used to ensure the normal operation of the system. After the second pipeline 20 and the third pipeline 21 are filled with heat transfer oil, the pump outlet degassing line 13 and the pump inlet degassing line 12 are opened to discharge the gas in the pipeline through the high-position expansion tank 1.

[0048] Then, the third sub-step is performed, the connection between the users to be heated or heated 8, 9, 10 and the second pipeline 20 is opened, and the users to be heated or heated 8, 9, 10 are filled with oil one by one. At the same time, the user degassing lines 14, 15, 16 are opened to perform exhaust operations. The exhaust gas of the users to be heated or heated 8, 9, 10 is collected by the oil-gas cooler 6, in which the oil is collected and transported to the low-temperature oil storage tank 2, and the gas can be vented as shown by the arrow.

[0049] Step 2, perform dehydration operation. When the temperature of the thermal oil reaches the preset temperature, the heater 5 enters the set value control mode, so that the temperature of the thermal oil is maintained at the set temperature, for example, 110°C. This stage is the constant temperature dehydration stage, and the generated water vapor is discharged through the user degassing lines 14, 15, 16, the pump outlet degassing line 13 and the pump inlet degassing line 12. The undischarged water vapor finally enters the oil-gas separator 3 through the third pipeline 21 and reaches the high-level expansion tank 1. The time of this constant temperature dehydration stage can be different according to different needs, for example, it can be two hours.

[0050] Step three, perform degassing operation. After the dehydration is completed, the temperature of the heat transfer oil rises simultaneously with the accompanying pipeline medium. The heater 5 is set to another preset temperature according to the heating curve requirements, and the light hydrocarbons in the heat transfer oil are removed during the heating to another preset temperature, such as about 250°C. In this process, the user degassing lines 14, 15, and 16 can be closed at intervals and opened at intervals. For example, based on experience, after the degassing reaches the initial target, the degassing lines 14, 15, and 16 are shut down to prevent the heat transfer oil from entering the oil-gas cooler 6 through the degassing lines 14, 15, and 16. After a period of time, such as half an hour, the user degassing lines 14, 15, and 16 are opened again to perform the exhaust operation. The valve from the gas outlet of the oil-gas separator 3 to the high-level expansion tank 1 remains open for degassing.

[0051] Step 4: Heat conduction is heated to the start-up temperature. After the light hydrocarbon removal step is completed, the heater 5 re-enters the automatic heating mode. After the heat transfer oil temperature reaches the temperature required by the heat tracing or the user, the heater 5 system enters the set value control mode and maintains the set temperature.

[0052] In one embodiment, the thermal oil system is applied to the start-up of a coal direct liquefaction unit, and the implementation method is as follows.

[0053] The high-level expansion tank 1 establishes the liquid level through the oil injection pump 7, and conducts to the process of the oil-gas separator 3 and the oil-gas cooler 6. Open the regulating valve on the fourth pipeline 11, start the circulation pump 4 to establish the circulation. Start the heater 5, set it to 80℃, and start heating. The high-level expansion tank 1 continues to inject heat transfer oil. As the oil volume and temperature of the system increase, the volume of the heat transfer oil also increases. At this time, by closing the regulating valve on the fourth pipeline 11, the heat transfer oil is transported to the second pipeline 20, and then transported to the third pipeline 21 through the user branch line, and then refluxed to the oil-gas separator 3. Control the liquid level of the high-level expansion tank 1 at 5%-50% to ensure normal operation. Keep the regulating valves of the users 8, 9, and 10 to be heated or heated in the closed state, and establish the heat transfer oil circulation through the user branch line 17. Open the pump inlet degassing line 12 and the pump outlet degassing line 13 for degassing. Confirm that the coal direct liquefaction device is ready. Open the users 8, 9, 10 to be heated or heated one by one, and simultaneously open the user degassing lines 14, 15, 16 of the users 8, 9, 10 to be heated or heated, and introduce the heat transfer oil into the users 8, 9, 10 to be heated or heated. In this embodiment, the users to be heated or heated can be pipeline jackets.

[0054] The temperature of heater 5 is set to 110° C. and heated at a constant temperature for 2 hours, mainly for dehydration.

[0055] The heat transfer oil is heated according to the heating curve, and the temperature is controlled by the heater 5. The heat transfer oil is heated to 150°C, and the flanges of the pipelines, valves, heaters, etc. of the heat transfer oil system are heat-tightened. The heat transfer oil is heated to 250°C and kept at a constant temperature for 2 hours to remove the light hydrocarbons in the heat transfer oil. During the heating process, the user's degassing line is opened every half an hour for exhaust. The oil-gas separator 3 to the high-level expansion tank 1 is kept open for degassing.

[0056] Adjust the set temperature of heater 5 to 350℃, and heater 5 will re-enter the automatic heating mode. Keep the temperature for half an hour after each 10℃ increase. When the temperature reaches 300℃, heat-tighten the structures in the thermal oil system, such as flanges, again. At this point, the thermal oil system is started.

[0057] In another embodiment, a heat transfer oil system is used to start up a polyglycolic acid device. The heat transfer oil mainly provides heat for various reactions and serves as pipeline heating. The specific implementation method is as follows.

[0058] The high-level expansion tank 1 establishes the liquid level through the oil injection pump 7, and conducts to the process of the oil-gas separator 3 and the oil-gas cooler 6. Open the regulating valve on the fourth pipeline 11, and start the circulation pump 4 to establish the circulation. Start the heater 5, set it to 100℃, and start heating. The high-level expansion tank 1 continues to inject heat transfer oil. As the oil volume and temperature of the system increase, the volume of the heat transfer oil also increases. At this time, by closing the regulating valve on the fourth pipeline 11, the heat transfer oil is transported to the second pipeline 20, and transported to the third pipeline 21 through the user branch line, and then refluxed to the oil-gas separator 3. Control the liquid level of the high-level expansion tank 1 at 10%-40%. Keep the regulating valve of the user to be heated or heated in the closed state, and establish the heat transfer oil circulation through the user branch line 17. Open the pump inlet degassing line 12 and the pump outlet degassing line 13 for degassing. Open the users 8, 9, 10 to be heated or heated one by one, and simultaneously open the user degassing lines 14, 15, 16 of the users 8, 9, 10 to be heated or heated, and introduce the heat transfer oil into the users 8, 9, 10 to be heated or heated.

[0059] The heat transfer oil temperature is 110°C and is heated at a constant temperature for 3 hours for dehydration.

[0060] The heat transfer oil is heated according to the heating curve, and the temperature is controlled by the heater 5. The heat transfer oil is heated to 150°C, and the flanges of the pipelines, valves, heaters, etc. of the heat transfer oil system are heat-tightened. The heat transfer oil is heated to 200°C and kept at a constant temperature for 2 hours to remove the light hydrocarbons in the heat transfer oil. During the heating process, the user's degassing lines 14, 15, and 16 are opened every half an hour for exhaust. The oil-gas separator 3 to the high-level expansion tank 1 is kept open for degassing.

[0061] Adjust the set temperature of heater 5 to 280℃, and heater 5 will re-enter the automatic heating mode. Keep the temperature for half an hour after each 10℃ increase. When the temperature reaches 250℃, heat tighten again. At this time, the thermal oil system is started.

[0062] The heating method of the heat transfer oil used in this application is electric heating, and the control method is to control the outlet temperature of the heat transfer oil of the electric heater. Of course, different heating methods can be selected according to different process flows. The structure is simple and easy to implement.

[0063] The present application uses a fourth pipeline from the heater to the inlet of the circulation pump to realize the system circulation at the start-up, and gradually injects the thermal oil into the system. This setting solves the problem of low temperature, high density, small volume and insufficient circulation volume of the thermal oil when starting the thermal oil circulation, thereby solving the problem of the circulation pump being emptied and the thermal oil system being unable to operate.

[0064] The present application is provided with degassing pipelines at multiple locations (for example, a pump outlet degassing line, a pump inlet degassing line, and a user degassing line, etc.), which can be used to degas to a high-level expansion tank or an oil-gas cooler to ensure the normal operation of the thermal oil system. During the start-up process, the above-mentioned setting is operated to degas, which can effectively discharge the gas in the user to be heated or heated, and prevent the circulating pump from being evacuated or vibrated and damaged. During the constant-temperature dehydration and light hydrocarbon removal process of the thermal oil system, the above-mentioned setting performs degassing operations regularly, and the gas generated by the thermal oil system due to the increase in temperature can be discharged to a high-level expansion tank or an oil-gas cooler in time to ensure the stable operation of the thermal oil system.

[0065] In this application, the oil-gas cooler can recover the oil and gas discharged from the degassing operation and the overpressure of the high-level expansion tank, as well as the liquid heat transfer oil entrained in the oil and gas. The outlet of the oil-gas cooler is connected to the low-level oil storage tank, and the non-condensable gas is discharged to the atmosphere. This setting can recover the volatile oil and gas, save costs, and reduce the pollution of the oil and gas emissions to the environment.

[0066] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and / or modifications that fall within the scope of the present invention, and changes and / or modifications made according to the embodiments of the present invention should be included within the scope of protection of the present invention.

Claims

1. A thermal oil system, characterized in that: include: A high-position expansion tank, the high-position expansion tank is used to store heat transfer oil, An oil-gas separator, the inlet of which is selectively connected to the oil outlet of the high-position expansion tank, a heater, wherein the inlet of the heater is connected to the oil outlet of the oil-gas separator through a first pipeline, A circulation pump is disposed on the first pipeline and selectively communicated with the heater and the oil-gas separator. The inlet of the user to be heated or heated is selectively connected to the outlet of the heater through a second pipeline, and the oil outlet of the user to be heated or heated is selectively connected to the inlet of the oil-gas separator through a third pipeline. The outlet of the heater is selectively connected to the first pipeline at the inlet end of the circulation pump through a fourth pipeline.

2. The thermal oil system according to claim 1, characterized in that: A user branch line is selectively connected between the second pipeline and the third pipeline, the user branch line is connected in parallel with the user to be heated or heated, and a pressure regulating valve is provided on the user branch line.

3. The thermal oil system according to claim 2, characterized in that: The third pipeline is selectively connected to the inlet of the high-level expansion tank through a pump inlet degassing line.

4. The thermal oil system according to any one of claims 1 to 3, characterized in that: The first pipeline at the outlet end of the circulation pump is selectively connected to the inlet of the high-level expansion tank through a pump outlet end degassing line.

5. The thermal oil system according to any one of claims 1 to 4, characterized in that: The gas outlet of the high-level expansion tank is connected to the inlet of the oil-gas cooler, the outlet of the oil-gas cooler is connected to the inlet of the low-level oil storage tank, and the outlet of the low-level oil storage tank is connected to the inlet of the high-level expansion tank through an oil injection pump.

6. The thermal oil system according to claim 5, characterized in that: The degassing port of the user to be heated or heated is selectively connected to the inlet of the oil-gas cooler through a user degassing line.

7. The thermal oil system according to claim 5 or 6, characterized in that: An unexpected branch is selectively provided between the third pipeline and the inlet of the low-level oil storage tank in a connected manner.

8. The thermal oil system according to any one of claims 1 to 7, characterized in that: The gas outlet of the oil-gas separator is connected to the inlet of the high-position expansion tank.

9. A method for starting up a thermal oil system according to any one of claims 1 to 8, characterized in that: include: Step 1: The heat transfer oil circulates in the heat transfer oil system and is initially heated. Step 2: The heat transfer oil is heated to the dehydration temperature and the dehydration operation is performed. Step 3: The heat transfer oil is heated to the degassing temperature and degassing is performed. Step 4: Heat the heat transfer oil to the start-up temperature.

10. The start-up method according to claim 9, characterized in that: Step one includes: In the first sub-step, the heat transfer oil is sent from the high-position expansion tank through the oil-gas separator to the heater by the circulation pump for heating, and the heated heat transfer oil is sent back to the inlet of the circulation pump by the fourth pipeline for circulation. The second sub-step is to reduce the amount of the heat transfer oil heated by the heater and returned to the inlet of the circulation pump, and to make the second pipeline and the third pipeline connected through the user branch line, and the heated heat transfer oil is sequentially returned to the oil-gas separator through the second pipeline, the user branch line and the third pipeline for circulation. The third sub-step is to connect the second pipeline with the third pipeline through the user to be heated or heated, and the heated heat transfer oil passes through the second pipeline, the user to be heated or heated, and the third pipeline in sequence and returns to the oil-gas separator for circulation.

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