A micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil

Abstract

This utility model discloses a micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil, installed on an offshore oil processing platform. It includes an inlet pressure regulating valve, an exhaust pressure regulating valve, a pressure sensor, and a controller. One end of the inlet pressure regulating valve is connected to an inert gas source, and the other end is connected to the gas inlet of the expansion tank. One end of the exhaust pressure regulating valve is connected to the gas outlet of the expansion tank, and the other end is connected to a safety venting device. The pressure sensor is installed on the expansion tank and used to monitor the pressure inside the tank in real time. The pressure sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to both the inlet and exhaust pressure regulating valves. This system can solve the problems of heat transfer oil leakage causing environmental pollution, burns, and fire risks caused by conventional breather valve solutions, as well as the problems of heat transfer oil contamination, oxidation, and deterioration caused by atmospheric entry.

Description

Technical Field

[0001] This utility model belongs to the field of safety technology for offshore platform equipment, specifically relating to a micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil. Background Technology

[0002] On offshore oil processing platforms, in order to ensure the flowability of crude oil and avoid pipeline blockage, equipment failure and difficulties in transportation, thermal oil electric heating systems are usually installed. Given the limited space, load-bearing capacity and extremely high safety standards of offshore oil processing platforms, thermal oil electric heating systems have a small footprint and are therefore widely used.

[0003] The electric heating system for thermal oil includes an electric heater that heats the thermal oil. The heated thermal oil circulates in the tube side and exchanges heat with the crude oil flowing in the shell side. The tube side includes a heating tube bundle, a tube box, and an expansion tank. During operation, the thermal oil expands and contracts due to temperature changes, causing fluctuations in the volume of the thermal oil and pressure fluctuations in the expansion tank.

[0004] The conventional solution is to install a breather valve on the expansion tank, which is set with a positive pressure opening threshold and a negative pressure (vacuum) opening threshold: when the pressure inside the expansion tank rises above the positive pressure opening threshold, the breather valve opens and exhausts air to the atmosphere; when the pressure inside the expansion tank drops below the negative pressure opening threshold, the breather valve opens and draws air in from the atmosphere. However, this conventional solution has the following significant drawbacks:

[0005] 1) Environmental pollution and safety hazards: During exhaust, the high-temperature heat transfer oil vapor or droplets in the expansion tank may be discharged into the atmosphere along with the gas, causing environmental pollution and posing serious safety hazards such as burns to personnel and fires caused by open flames.

[0006] 2) Heat transfer oil contamination and oxidation: During air intake, oxygen, moisture and impurities in the atmosphere enter the expansion tank, causing the heat transfer oil to be contaminated, oxidized and deteriorated, thereby shortening its service life and increasing operation and maintenance costs.

[0007] Actual measurements show that conventional breather valve solutions result in an annual heat transfer oil loss rate of 3-5%, and pose a risk of exceeding the lower limit of atmospheric flammable substances. Therefore, there is an urgent need for a safer, more environmentally friendly expansion tank pressure maintenance solution that can effectively protect the heat transfer oil. Utility Model Content

[0008] In view of the above-mentioned defects of the prior art, the present invention provides a micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil, which can solve the problems of heat transfer oil leakage causing environmental pollution, burns and fire risks caused by conventional breather valve solutions, as well as the problems of heat transfer oil pollution, oxidation and deterioration caused by atmospheric entry.

[0009] The technical solution adopted by this utility model to solve its technical problem is:

[0010] A micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil, installed on an offshore oil processing platform, includes an inlet pressure regulating valve, an exhaust pressure regulating valve, a pressure sensor, and a controller. One end of the inlet pressure regulating valve is connected to an inert gas source, and the other end is connected to the gas inlet of the expansion tank. One end of the exhaust pressure regulating valve is connected to the gas outlet of the expansion tank, and the other end is connected to a safety venting device. The pressure sensor is installed on the expansion tank and is used to monitor the pressure inside the expansion tank in real time. The pressure sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to both the inlet pressure regulating valve and the exhaust pressure regulating valve. When the pressure inside the expansion tank is lower than the inlet pressure threshold, the inlet pressure regulating valve opens or its opening increases; when the pressure inside the expansion tank is higher than the exhaust pressure threshold, the exhaust pressure regulating valve opens or its opening increases.

[0011] Furthermore, the range of the intake pressure threshold is 1-2 kPa, and the range of the exhaust pressure threshold is 8-10 kPa.

[0012] Furthermore, the upstream side of the intake pressure regulating valve is provided with an upstream intake shut-off valve and the downstream side is provided with an intake downstream shut-off valve. An intake bypass shut-off valve and an intake bypass regulating valve are provided between the upstream side of the upstream intake shut-off valve and the downstream side of the intake downstream shut-off valve. The upstream intake shut-off valve, the intake pressure regulating valve, and the intake downstream shut-off valve are connected in series on the intake main pipeline. The intake bypass shut-off valve and the intake bypass regulating valve are connected in series on the intake bypass pipeline. The upstream ends of the intake main pipeline and the intake bypass pipeline are connected to the downstream end of the intake upstream main pipeline. The upstream end of the intake upstream main pipeline is used to connect to an inert gas source. The downstream ends of the intake main pipeline and the intake bypass pipeline are connected to the upstream end of the intake downstream main pipeline. The downstream end of the intake downstream main pipeline is used to connect to the gas inlet of the expansion tank.

[0013] Furthermore, an upstream intake vent pipe is connected to the main intake pipe between the intake pressure regulating valve and the upstream intake shut-off valve. An upstream intake vent valve is installed on the upstream intake vent pipe, and an upstream intake plug is connected to the free end of the upstream intake vent pipe downstream of the upstream intake vent valve. A downstream intake vent pipe is connected to the main intake pipe between the intake pressure regulating valve and the downstream intake shut-off valve. A downstream intake vent valve is installed on the downstream intake vent pipe, and a downstream intake plug is connected to the free end of the downstream intake vent pipe downstream of the downstream intake vent valve.

[0014] Furthermore, the exhaust pressure regulating valve has an upstream exhaust shut-off valve on its upstream side and an exhaust downstream shut-off valve on its downstream side. An exhaust bypass shut-off valve and an exhaust bypass regulating valve are provided between the upstream side of the exhaust upstream shut-off valve and the downstream side of the exhaust downstream shut-off valve. The exhaust upstream shut-off valve, the exhaust pressure regulating valve, and the exhaust downstream shut-off valve are connected in series on the exhaust main pipeline. The exhaust bypass shut-off valve and the exhaust bypass regulating valve are connected in series on the exhaust bypass pipeline. The upstream ends of the exhaust main pipeline and the exhaust bypass pipeline are connected to the downstream end of the exhaust upstream main pipeline. The upstream end of the exhaust upstream main pipeline is used to connect to the gas outlet of the expansion tank. The downstream ends of the exhaust main pipeline and the exhaust bypass pipeline are connected to the upstream end of the exhaust downstream main pipeline. The downstream end of the exhaust downstream main pipeline is used to connect to the safety venting equipment.

[0015] Furthermore, an upstream exhaust venting pipe is connected to the main exhaust pipe between the exhaust pressure regulating valve and the upstream exhaust shut-off valve. An upstream exhaust purging valve is installed on the upstream exhaust venting pipe, and an upstream exhaust plug is connected to the free end of the upstream exhaust venting pipe downstream of the upstream exhaust purging valve. A downstream exhaust venting pipe is connected to the main exhaust pipe between the exhaust pressure regulating valve and the downstream exhaust shut-off valve. A downstream exhaust purging valve is installed on the downstream exhaust venting pipe, and a downstream exhaust plug is connected to the free end of the downstream exhaust venting pipe downstream of the downstream exhaust purging valve.

[0016] Furthermore, the pressure sensor is a pressure transmitter, the controller is a PIC controller, the signal output terminal of the PIC controller is connected to the intake pressure regulating valve through the intake PY converter, and the signal output terminal of the PIC controller is also connected to the exhaust pressure regulating valve through the exhaust PY converter.

[0017] Furthermore, the upstream main intake pipe is equipped with an intake main shut-off valve and a check valve in sequence according to the flow direction, the inert gas source is a nitrogen source, and the safety venting device is a safety venting main pipe or a flare system.

[0018] Furthermore, an intake figure-eight blind flange is provided on the downstream main intake pipe, and an exhaust figure-eight blind flange is provided on the upstream main exhaust pipe.

[0019] Furthermore, the upstream end of the intake pressure regulating valve is connected to the intake main pipe via an upstream intake reducer, and the downstream end of the intake pressure regulating valve is connected to the intake main pipe via a downstream intake reducer; the upstream end of the exhaust pressure regulating valve is connected to the exhaust main pipe via an upstream exhaust reducer, and the downstream end of the exhaust pressure regulating valve is connected to the exhaust main pipe via a downstream exhaust reducer.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0021] The micro-positive pressure maintenance system for the expansion tank of electrically heated heat transfer oil in this invention is installed on an offshore oil processing platform. It includes an inlet pressure regulating valve, an exhaust pressure regulating valve, a pressure sensor, and a controller. One end of the inlet pressure regulating valve is connected to an inert gas source and the other end is connected to the gas inlet of the expansion tank. One end of the exhaust pressure regulating valve is connected to the gas outlet of the expansion tank and the other end is connected to a safety venting device. The pressure sensor is installed on the expansion tank and is used to monitor the pressure inside the expansion tank in real time. The pressure sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the inlet pressure regulating valve and the exhaust pressure regulating valve, respectively. This system uses a pressure sensor to monitor the pressure inside the expansion tank in real time and transmits the data to the controller. When the received pressure inside the expansion tank is lower than the inlet pressure threshold, the controller opens or increases the opening of the inlet pressure regulating valve, allowing inert gas from the inert gas source to enter the expansion tank and increase the pressure inside. When the received pressure inside the expansion tank is higher than the inlet pressure threshold, the controller closes or decreases the opening of the inlet pressure regulating valve. When the received pressure inside the expansion tank is higher than the exhaust pressure threshold, the controller opens or increases the opening of the exhaust pressure regulating valve, allowing gas from the expansion tank to enter the safety venting device and reduce the pressure inside the expansion tank. When the received pressure inside the expansion tank is lower than the exhaust pressure threshold, the controller... The controller closes or reduces the opening of the exhaust pressure regulating valve, thus ensuring that the pressure inside the expansion tank is maintained at a slightly positive pressure. This system completely eliminates the need for a breather valve that directly connects to the atmosphere, and uses a closed expansion tank slightly positive pressure maintenance system for pressure compensation and release. This fundamentally eliminates the possibility of high-temperature heat transfer oil vapor or droplets being released into the atmosphere from the expansion tank, completely eliminating the environmental pollution, burns to personnel, and potential fire and explosion hazards caused by this, and significantly improving the safety of offshore oil processing platform operations. This system uses inert gas to isolate the system from the atmosphere, preventing oxygen, moisture, and impurities from the atmosphere from entering the expansion tank, avoiding oxidation, contamination, and deterioration of the heat transfer oil, extending the service life of the heat transfer oil, and reducing system maintenance costs and replacement expenses caused by heat transfer oil deterioration.

[0022] In summary, the micro-positive pressure maintenance system for the expansion tank of this electrically heated heat transfer oil can solve the problems of heat transfer oil leakage causing environmental pollution, burns, and fire risks, as well as the pollution, oxidation, and deterioration of heat transfer oil caused by atmospheric entry, which are common with conventional breather valve solutions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the micro-positive pressure maintenance system of the expansion tank of the electrically heated heat transfer oil.

[0024] Explanation of reference numerals in the diagram: 1. Inlet pressure regulating valve; 2. Exhaust pressure regulating valve; 3. Pressure transmitter; 4. PIC controller; 5. Nitrogen source; 6. Expansion tank; 7. Safety venting device; 8. Inlet upstream shut-off valve; 9. Inlet downstream shut-off valve; 10. Inlet bypass shut-off valve; 11. Inlet bypass regulating valve; 12. Inlet main pipeline; 13. Inlet bypass pipeline; 14. Inlet upstream main pipeline; 15. Inlet downstream main pipeline; 16. Inlet upstream vent pipeline; 17. Inlet upstream drain valve; 18. Inlet upstream plug; 19. Inlet downstream vent pipeline; 20. Inlet downstream drain valve; 21. Inlet downstream plug; 22. Exhaust upstream shut-off valve; 23. Exhaust downstream shut-off valve; 24. Exhaust bypass shut-off valve; 25. Exhaust bypass valve. 26. Main exhaust pipe, 27. Exhaust bypass pipe, 28. Upstream exhaust main pipe, 29. Downstream exhaust main pipe, 30. Upstream exhaust vent pipe, 31. Upstream exhaust drain valve, 32. Upstream exhaust plug, 33. Downstream exhaust vent pipe, 34. Downstream exhaust drain valve, 35. Downstream exhaust plug, 36. Main intake shut-off valve, 37. Check valve, 38. Intake figure-eight blind flange, 39. Exhaust figure-eight blind flange, 40. Upstream intake reducer, 41. Downstream intake reducer, 42. Upstream exhaust reducer, 43. Downstream exhaust reducer, 44. Intake PY converter, 45. Exhaust PY converter, 46. Electric heater, 47. Crude oil inlet pipe, 48. Crude oil outlet pipe. Detailed Implementation

[0025] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings. These embodiments are only used to illustrate this utility model and are not intended to limit it.

[0026] In the description of this utility model, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this utility model. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0028] like Figure 1 As shown, a micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil is installed on an offshore oil processing platform. It includes an inlet pressure regulating valve 1, an exhaust pressure regulating valve 2, a pressure sensor, and a controller. One end of the inlet pressure regulating valve 1 is connected to an inert gas source, and the other end is connected to the gas inlet of the expansion tank 6. One end of the exhaust pressure regulating valve 2 is connected to the gas outlet of the expansion tank 6, and the other end is connected to a safety venting device 7. The pressure sensor is installed on the expansion tank 6 and is used to monitor the pressure inside the expansion tank 6 in real time. The pressure sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to both the inlet pressure regulating valve 1 and the exhaust pressure regulating valve 2. When the pressure inside the expansion tank 6 is lower than the inlet pressure threshold, the inlet pressure regulating valve 1 opens or its opening increases. When the pressure inside the expansion tank 6 is higher than the exhaust pressure threshold, the exhaust pressure regulating valve 2 opens or its opening increases.

[0029] In this way, the pressure sensor monitors the pressure inside the expansion tank 6 in real time and transmits the data to the controller. When the received pressure inside the expansion tank 6 is lower than the inlet pressure threshold, the controller controls the inlet pressure regulating valve 1 to open or increase its opening. Inert gas from the inert gas source enters the expansion tank 6 through the inlet pressure regulating valve 1 to increase the pressure inside the expansion tank 6. When the received pressure inside the expansion tank 6 is higher than the inlet pressure threshold, the controller controls the inlet pressure regulating valve 1 to close or decrease its opening. When the received pressure inside the expansion tank 6 is higher than the exhaust pressure threshold, the controller controls the exhaust pressure regulating valve 2 to open or increase its opening. Excess gas in the expansion tank 6 enters the safety venting device 7 through the exhaust pressure regulating valve 2 to reduce the pressure inside the expansion tank 6. When the received pressure inside the expansion tank 6 is lower than the exhaust pressure threshold, the controller controls the exhaust pressure regulating valve 2 to close or decrease its opening. Therefore, the pressure inside the expansion tank 6 can be maintained at a slightly positive pressure.

[0030] This system completely eliminates the need for a breather valve that directly connects to the atmosphere. Instead, it employs a closed expansion tank 6 with a slightly positive pressure maintenance system for pressure compensation and release. This fundamentally prevents the release of high-temperature heat transfer oil vapor or droplets from the expansion tank 6 into the atmosphere, thus completely eliminating the environmental pollution, burns to personnel, and potential fire and explosion hazards caused by such releases. This significantly improves the operational safety of offshore oil processing platforms. Furthermore, the system utilizes inert gas to isolate the system from the atmosphere, preventing atmospheric oxygen, moisture, and impurities from entering the expansion tank 6. This avoids oxidation, contamination, and deterioration of the heat transfer oil, extends its service life, and reduces system maintenance and replacement costs caused by heat transfer oil deterioration.

[0031] In one embodiment, the intake pressure threshold ranges from 1 to 2 kPa, and the exhaust pressure threshold ranges from 8 to 10 kPa.

[0032] In one embodiment,

[0033] An upstream intake shut-off valve 8 is provided on the upstream side of the intake pressure regulating valve 1, and a downstream intake shut-off valve 9 is provided on the downstream side. An intake bypass shut-off valve 10 and an intake bypass regulating valve 11 are provided between the upstream side of the upstream intake shut-off valve 8 and the downstream side of the downstream intake shut-off valve 9. The upstream intake shut-off valve 8, the intake pressure regulating valve 1, and the downstream intake shut-off valve 9 are connected in series on the intake main pipeline 12. The intake bypass shut-off valve 10 and the intake bypass regulating valve 11 are connected in series on the intake bypass pipeline 13. The upstream ends of the intake main pipeline 12 and the intake bypass pipeline 13 are connected to the downstream end of the intake upstream main pipeline 14. The upstream end of the intake upstream main pipeline 14 is used to connect to an inert gas source. The downstream ends of the intake main pipeline 12 and the intake bypass pipeline 13 are connected to the upstream end of the intake downstream main pipeline 15. The downstream end of the intake downstream main pipeline 15 is used to connect to the gas inlet of the expansion tank 6.

[0034] The upstream intake shut-off valve 8 and the downstream intake shut-off valve 9 are normally open, while the intake bypass shut-off valve 10 and the intake bypass regulating valve 11 are normally closed. When the intake pressure regulating valve 1 malfunctions and needs maintenance, the upstream intake shut-off valve 8 and the downstream intake shut-off valve 9 need to be closed to isolate the intake pressure regulating valve 1 from the inert gas source and the expansion tank 6, ensuring operational safety. The intake bypass shut-off valve 10 and the intake bypass regulating valve 11 need to be temporarily opened, and the amount of inert gas entering the expansion tank 6 can be manually controlled through the intake bypass regulating valve 11 to achieve manual control of the pressure inside the expansion tank 6. The intake bypass shut-off valve 10 has an emergency shut-off function.

[0035] In a first preferred embodiment, an upstream intake vent pipe 16 is connected to the main intake pipe 12 between the intake pressure regulating valve 1 and the upstream intake shut-off valve 8. An upstream intake vent valve 17 is provided on the upstream intake vent pipe 16, and an upstream intake plug 18 is connected to the free end of the upstream intake vent pipe 16 downstream of the upstream intake vent valve 17. A downstream intake vent pipe 19 is connected to the main intake pipe 12 between the intake pressure regulating valve 1 and the downstream intake shut-off valve 9. A downstream intake vent valve 20 is provided on the downstream intake vent pipe 19, and a downstream intake plug 21 is connected to the free end of the downstream intake vent pipe 19 downstream of the downstream intake vent valve 20.

[0036] When the intake pressure regulating valve 1 needs maintenance, first close the upstream intake shut-off valve 8 and the downstream intake shut-off valve 9. Then, remove the upstream intake plug 18 and the downstream intake plug 21 and open the upstream intake vent valve 17 and the downstream intake vent valve 20. This allows the condensate or impurities accumulated in the intake main pipe 12 between the intake pressure regulating valve 1 and the upstream intake shut-off valve 8 to be drained through the upstream intake vent valve 17. Similarly, the condensate or impurities accumulated in the intake main pipe 12 between the intake pressure regulating valve 1 and the downstream intake shut-off valve 9 are drained through the downstream intake vent valve 20. Finally, the condensate or impurities accumulated in the intake pressure regulating valve 1 are drained through the upstream intake vent valve 17 and the downstream intake vent valve 20, thus keeping the intake main pipe 12 unobstructed.

[0037] The upstream end of the intake upstream vent pipe 16 is at a higher height than the downstream end, and the upstream end of the intake upstream vent pipe 16 is at the same height as the low point of the intake main pipe 12. The upstream end of the intake downstream vent pipe 19 is at a higher height than the downstream end, and the upstream end of the intake downstream vent pipe 19 is at the same height as the low point of the intake main pipe 12.

[0038] This allows condensate or impurities accumulated in the main intake pipe 12 between the upstream intake shut-off valve 8 and the downstream intake shut-off valve 9 to be automatically drained by gravity, and also allows condensate or impurities accumulated in the intake pressure regulating valve 1 to be automatically drained by gravity.

[0039] In the second preferred embodiment,

[0040] An upstream exhaust pressure regulating valve 2 is provided with an upstream exhaust shut-off valve 22 and a downstream exhaust shut-off valve 23. An exhaust bypass shut-off valve 24 and an exhaust bypass regulating valve 25 are provided between the upstream side of the upstream exhaust shut-off valve 22 and the downstream side of the exhaust downstream shut-off valve 23. The upstream exhaust shut-off valve 22, the exhaust pressure regulating valve 2, and the exhaust downstream shut-off valve 23 are connected in series on the main exhaust pipe 26. The exhaust bypass shut-off valve 24 and the exhaust bypass regulating valve 25 are connected in series on the exhaust bypass pipe 27. The upstream ends of the main exhaust pipe 26 and the exhaust bypass pipe 27 are connected to the downstream end of the upstream exhaust main pipe 28. The upstream end of the upstream exhaust main pipe 28 is used to connect to the gas outlet of the expansion tank 6. The downstream ends of the main exhaust pipe 26 and the exhaust bypass pipe 27 are connected to the upstream end of the downstream exhaust main pipe 29. The downstream end of the downstream exhaust main pipe 29 is used to connect to the safety venting device 7.

[0041] The upstream exhaust shut-off valve 22 and the downstream exhaust shut-off valve 23 are normally open, while the exhaust bypass shut-off valve 24 and the exhaust bypass regulating valve 25 are normally closed. When the exhaust pressure regulating valve 2 malfunctions and needs maintenance, the upstream exhaust shut-off valve 22 and the downstream exhaust shut-off valve 23 need to be closed to isolate the exhaust pressure regulating valve 2 from the expansion tank 6 and the safety venting device 7, ensuring operational safety. The exhaust bypass shut-off valve 24 and the exhaust bypass regulating valve 25 need to be temporarily opened, and the amount of gas discharged from the expansion tank 6 is manually controlled through the exhaust bypass regulating valve 25 to achieve manual control of the pressure inside the expansion tank 6. The exhaust bypass shut-off valve 24 has an emergency shut-off function.

[0042] Among them, an upstream exhaust venting pipe 30 is connected to the main exhaust pipe 26 between the exhaust pressure regulating valve 2 and the upstream exhaust shut-off valve 22. An upstream exhaust venting valve 31 is provided on the upstream exhaust venting pipe 30. An upstream exhaust plug 32 is connected to the free end of the upstream exhaust venting pipe 30 downstream of the upstream exhaust venting valve 31. A downstream exhaust venting pipe 33 is connected to the main exhaust pipe 26 between the exhaust pressure regulating valve 2 and the downstream exhaust shut-off valve 23. A downstream exhaust venting valve 34 is provided on the downstream exhaust venting pipe 33. A downstream exhaust plug 35 is connected to the free end of the downstream exhaust venting pipe 33 downstream of the downstream exhaust venting valve 34.

[0043] When the exhaust pressure regulating valve 2 needs to be inspected, first close the exhaust upstream shut-off valve 22 and the exhaust downstream shut-off valve 23. Then, remove the exhaust upstream plug 32 and the exhaust downstream plug 35 and open the exhaust upstream drain valve 31 and the exhaust downstream drain valve 34. The exhaust upstream drain valve 31 will drain the condensate or impurities accumulated in the exhaust main pipeline 26 between the exhaust pressure regulating valve 2 and the exhaust upstream shut-off valve 22. The exhaust downstream drain valve 34 will drain the condensate or impurities accumulated in the exhaust main pipeline 26 between the exhaust pressure regulating valve 2 and the exhaust downstream shut-off valve 23. The exhaust upstream drain valve 31 and the exhaust downstream drain valve 34 will drain the condensate or impurities accumulated in the exhaust pressure regulating valve 2, so as to keep the exhaust main pipeline 26 unobstructed.

[0044] Preferably, the upstream end of the exhaust upstream vent pipe 30 is at a higher height than the downstream end, and the upstream end of the exhaust upstream vent pipe 30 is at the same height as the low point of the exhaust main pipe 26. The upstream end of the exhaust downstream vent pipe 33 is at a higher height than the downstream end, and the upstream end of the exhaust downstream vent pipe 33 is at the same height as the low point of the exhaust main pipe 26.

[0045] This allows condensate or impurities accumulated in the main exhaust pipe 26 between the upstream exhaust shut-off valve 22 and the downstream exhaust shut-off valve 23 to be automatically drained by gravity, and also allows condensate or impurities accumulated in the exhaust pressure regulating valve 2 to be automatically drained by gravity.

[0046] Among them, the downstream main intake pipe 15 is equipped with an intake figure-eight blind flange 38, and the upstream main exhaust pipe 28 is equipped with an exhaust figure-eight blind flange 39.

[0047] By inserting the hollow plate of the intake figure-eight blind flange 38 into the downstream main intake pipe 15, the downstream main intake pipe 15 is opened for conduction. By inserting the hollow plate of the exhaust figure-eight blind flange 39 into the upstream main exhaust pipe 28, the upstream main exhaust pipe 28 is opened for conduction, thereby connecting the system with the expansion tank 6. By inserting the solid plate of the intake figure-eight blind flange 38 into the downstream main intake pipe 15, the downstream main intake pipe 15 is blocked. By inserting the solid plate of the exhaust figure-eight blind flange 39 into the upstream main exhaust pipe 28, the upstream main exhaust pipe 28 is blocked, thereby physically isolating the system from the expansion tank 6, thus facilitating the maintenance of the expansion tank 6.

[0048] The upstream end of the intake pressure regulating valve 1 is connected to the intake main pipe 12 via the intake upstream reducer 40, and the downstream end of the intake pressure regulating valve 1 is connected to the intake main pipe 12 via the intake downstream reducer 41; the upstream end of the exhaust pressure regulating valve 2 is connected to the exhaust main pipe 26 via the exhaust upstream reducer 42, and the downstream end of the exhaust pressure regulating valve 2 is connected to the exhaust main pipe 26 via the exhaust downstream reducer 43.

[0049] In the third preferred embodiment, an intake main shut-off valve 36 and a one-way valve 37 are sequentially arranged in the flow direction on the upstream main intake pipe 14. The inert gas source is a nitrogen source 5, which is a nitrogen cylinder group or a nitrogen generator. The safety venting device 7 is a safety venting main pipe or a flare system. The one-way valve 37 is used to prevent the inert gas from flowing back. The intake main shut-off valve 36 is normally open and only needs to be closed in emergencies or when the expansion tank 6 is under maintenance.

[0050] In one embodiment, the pressure sensor is a pressure transmitter 3, the controller is a PIC controller 4, the signal output terminal of the PIC controller 4 is connected to the intake pressure regulating valve 1 through the intake PY converter 44, and the signal output terminal of the PIC controller 4 is also connected to the exhaust pressure regulating valve 2 through the exhaust PY converter 45.

[0051] This system has a simple and compact structure, making it particularly suitable for the space-constrained environment of offshore oil processing platforms. During installation, only the following components need to be arranged in the available space on the offshore oil processing platform: intake pressure regulating valve 1, upstream intake shut-off valve 8, downstream intake shut-off valve 9, intake bypass shut-off valve 10, intake bypass regulating valve 11, upstream intake vent valve 17, downstream intake vent valve 20, exhaust pressure regulating valve 2, upstream exhaust shut-off valve 22, downstream exhaust shut-off valve 23, exhaust bypass shut-off valve 24, exhaust bypass regulating valve 25, upstream exhaust vent valve 31, and downstream exhaust vent valve 34. The system can then be connected to the existing inert gas source, expansion tank 6, and safety venting equipment 7 via pipelines. The modification work is minimal, and it is easy to implement and promote.

[0052] Among them, the upstream intake shut-off valve 8, the downstream intake shut-off valve 9, the intake bypass shut-off valve 10, the intake bypass regulating valve 11, the upstream intake vent valve 17, the downstream intake vent valve 20, the upstream exhaust shut-off valve 22, the downstream exhaust shut-off valve 23, the exhaust bypass shut-off valve 24, the exhaust bypass regulating valve 25, the upstream exhaust vent valve 31, and the downstream exhaust vent valve 34 are all ball valves, gate valves, and stop valves.

[0053] The system design takes into account the needs for maintenance bypass and drainage, which facilitates daily maintenance and fault handling, and ensures long-term stable operation of the system.

[0054] This system can reduce the annual loss rate of heat transfer oil from the original 3-5% to 0.2%, eliminate the emission of combustibles, reduce the fire and explosion risk area by 80%, and extend the maintenance cycle of expansion tank 6 from the original 3 months to 2 years.

[0055] The electric heater for the heat transfer oil is... Figure 1 Number 46 in the middle Figure 1 The label 47 indicates that crude oil enters the pipeline, and the label 48 indicates that crude oil exits the pipeline.

[0056] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present utility model, and these improvements and substitutions should also be considered within the protection scope of the present utility model.

Claims

1. A micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil, installed on an offshore oil processing platform, characterized in that: The system includes an intake pressure regulating valve (1), an exhaust pressure regulating valve (2), a pressure sensor, and a controller. One end of the intake pressure regulating valve (1) is connected to an inert gas source, and the other end is connected to the gas inlet of the expansion tank (6). One end of the exhaust pressure regulating valve (2) is connected to the gas outlet of the expansion tank (6), and the other end is connected to a safety venting device (7). The pressure sensor is installed on the expansion tank (6) and is used to monitor the pressure inside the expansion tank (6) in real time. The pressure sensor is connected to the signal input terminal of the controller, and the signal output terminal of the controller is connected to the intake pressure regulating valve (1) and the exhaust pressure regulating valve (2) respectively. When the pressure inside the expansion tank (6) is lower than the intake pressure threshold, the intake pressure regulating valve (1) opens or its opening degree increases. When the pressure inside the expansion tank (6) is higher than the exhaust pressure threshold, the exhaust pressure regulating valve (2) opens or its opening degree increases.

2. The micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil according to claim 1, characterized in that: The range of the intake pressure threshold is 1-2 kPa, and the range of the exhaust pressure threshold is 8-10 kPa.

3. The micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil according to claim 1, characterized in that: An upstream intake shut-off valve (8) is provided on the upstream side of the intake pressure regulating valve (1), and a downstream intake shut-off valve (9) is provided on the downstream side. An intake bypass shut-off valve (10) and an intake bypass regulating valve (11) are provided between the upstream side of the upstream intake shut-off valve (8) and the downstream side of the downstream intake shut-off valve (9). The upstream intake shut-off valve (8), the intake pressure regulating valve (1), and the downstream intake shut-off valve (9) are connected in series on the intake main pipeline (12). The intake bypass shut-off valve (10) and the intake bypass regulating valve (11) are provided in series. The valve (11) is connected in series with the intake bypass pipe (13). The upstream ends of the intake main pipe (12) and the intake bypass pipe (13) are connected to the downstream end of the intake upstream main pipe (14). The upstream end of the intake upstream main pipe (14) is used to connect to the inert gas source. The downstream ends of the intake main pipe (12) and the intake bypass pipe (13) are connected to the upstream end of the intake downstream main pipe (15). The downstream end of the intake downstream main pipe (15) is used to connect to the gas inlet of the expansion tank (6).

4. The micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil according to claim 3, characterized in that: An upstream intake vent pipe (16) is connected to the main intake pipe (12) between the intake pressure regulating valve (1) and the upstream intake shut-off valve (8). An upstream intake vent valve (17) is provided on the upstream intake vent pipe (16). An upstream intake plug (18) is connected to the free end of the upstream intake vent pipe (16) downstream of the upstream intake vent valve (17). A downstream intake vent pipe (19) is connected to the main intake pipe (12) between the intake pressure regulating valve (1) and the downstream intake shut-off valve (9). A downstream intake vent valve (20) is provided on the downstream intake vent pipe (19). A downstream intake plug (21) is connected to the free end of the downstream intake vent pipe (19) downstream of the downstream intake vent valve (20).

5. The micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil according to claim 3, characterized in that: The exhaust pressure regulating valve (2) has an upstream exhaust shut-off valve (22) on its upstream side and an exhaust downstream shut-off valve (23) on its downstream side. An exhaust bypass shut-off valve (24) and an exhaust bypass regulating valve (25) are provided between the upstream side of the exhaust upstream shut-off valve (22) and the downstream side of the exhaust downstream shut-off valve (23). The exhaust upstream shut-off valve (22), the exhaust pressure regulating valve (2), and the exhaust downstream shut-off valve (23) are connected in series on the exhaust main pipeline (26). The exhaust bypass shut-off valve (24) and the exhaust bypass regulating valve (25) are connected in series on the exhaust main pipeline (26). A throttle valve (25) is connected in series with an exhaust bypass pipe (27). The upstream ends of the exhaust main pipe (26) and the exhaust bypass pipe (27) are connected to the downstream end of the exhaust upstream main pipe (28). The upstream end of the exhaust upstream main pipe (28) is used to connect to the gas outlet of the expansion tank (6). The downstream ends of the exhaust main pipe (26) and the exhaust bypass pipe (27) are connected to the upstream end of the exhaust downstream main pipe (29). The downstream end of the exhaust downstream main pipe (29) is used to connect to the safety venting device (7).

6. The micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil according to claim 5, characterized in that: An upstream exhaust pipe (30) is connected to the main exhaust pipe (26) between the exhaust pressure regulating valve (2) and the upstream exhaust shut-off valve (22). An upstream exhaust venting pipe (30) is provided on the upstream exhaust venting pipe (30). An upstream exhaust drain valve (31) is provided on the upstream exhaust drain pipe (30) downstream of the upstream exhaust drain valve (31). An upstream exhaust plug (32) is connected to the free end of the upstream exhaust venting pipe (30) downstream of the upstream exhaust drain valve (31). A downstream exhaust venting pipe (33) is connected to the main exhaust pipe (26) between the exhaust pressure regulating valve (2) and the downstream exhaust shut-off valve (23). A downstream exhaust drain valve (34) is provided on the downstream exhaust venting pipe (33). A downstream exhaust plug (35) is connected to the free end of the downstream exhaust venting pipe (33) downstream of the downstream exhaust drain valve (34).

7. The micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil according to claim 1, characterized in that: The pressure sensor is a pressure transmitter (3), the controller is a PIC controller (4), the signal output terminal of the PIC controller (4) is connected to the intake pressure regulating valve (1) through the intake PY converter (44), and the signal output terminal of the PIC controller (4) is also connected to the exhaust pressure regulating valve (2) through the exhaust PY converter (45).

8. The micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil according to claim 3, characterized in that: The upstream main intake pipe (14) is equipped with an intake main shut-off valve (36) and a one-way valve (37) in sequence according to the flow direction. The inert gas source is a nitrogen source (5), and the safety venting device (7) is a safety venting main pipe or a flare system.

9. A micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil according to claim 5, characterized in that: The downstream main intake pipe (15) is provided with an intake figure-eight blind flange (38), and the upstream main exhaust pipe (28) is provided with an exhaust figure-eight blind flange (39).

10. A micro-positive pressure maintenance system for an expansion tank of electrically heated heat transfer oil according to claim 5, characterized in that: The upstream end of the intake pressure regulating valve (1) is connected to the intake main pipe (12) through the intake upstream reducer (40), and the downstream end of the intake pressure regulating valve (1) is connected to the intake main pipe (12) through the intake downstream reducer (41); the upstream end of the exhaust pressure regulating valve (2) is connected to the exhaust main pipe (26) through the exhaust upstream reducer (42), and the downstream end of the exhaust pressure regulating valve (2) is connected to the exhaust main pipe (26) through the exhaust downstream reducer (43).

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