A terminal oil gas recovery system

Abstract

The application discloses a wharf oil gas recovery system and relates to the technical field of oil gas recovery, which comprises an oil gas system and a refrigeration system, wherein the oil gas system comprises a cooling oil gas system and a hot melting oil gas system, the oil gas system is used for cooling oil gas, the cooling oil gas system cools oil gas to a designed temperature, and oil gas is normally condensed and liquefied; the hot melting oil gas system melts solid oil products blocked by ice in an oil gas passage, when ice blocking occurs in one of the oil gas passages, the system is switched to another oil gas passage, the requirement of continuous operation of wharf oil gas recovery facilities is met, the oil gas self-melting frost process is adopted, heat exchange tubes are prevented from being suddenly cooled and heated, heat exchanger leakage risks are reduced, and long-term and stable operation of the unit is ensured, the refrigeration system comprises a first-stage refrigeration system, a second-stage refrigeration system and a third-stage refrigeration system, the first-stage refrigeration system always keeps a refrigeration mode, and the stability is high; the first-stage refrigeration system not only guarantees continuous operation of wharf oil gas recovery facilities, but also helps the refrigeration system to stably and long-term operate.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas recovery technology, specifically a port oil and gas recovery system. Background Technology

[0002] Currently, with the continuous advancement of green port and low-carbon terminal construction, the number of oil and gas recovery systems and related facilities built to support port terminals are increasing and their coverage is expanding. At present, the oil and gas recovery devices put into operation at terminals are mainly used to collect and process a large amount of oil and gas volatilized during ship loading operations, reduce the fugitive emissions of volatile organic compounds, and play a significant role in improving air quality in port areas and reducing air pollutant emissions.

[0003] However, judging from the actual operation of oil and gas recovery systems, the performance of various terminal oil and gas recovery systems varies in terms of operational stability, processing efficiency, and energy consumption. The overall application effect is significantly different. Existing terminal oil and gas recovery facilities still have prominent technical shortcomings, mainly concentrated in two core issues: insufficient operational stability of the refrigeration system and high energy consumption of the entire unit. These issues restrict the efficient, economical, and long-term stable operation of oil and gas recovery devices. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects in the prior art. The oil and gas recovery system provided by this invention solves the technical problems of weak stability and high energy consumption of the refrigeration system during oil and gas recovery at the dock.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a terminal oil and gas recovery system, comprising: The oil and gas system includes a buffer tank, an induced draft fan, a regenerative heat exchanger, a primary heat exchanger, a secondary heat exchanger A, a secondary heat exchanger B, a tertiary heat exchanger A, and a tertiary heat exchanger B. After being buffered and stabilized by the buffer tank, the oil and gas are sent into the regenerative heat exchanger by the induced draft fan for initial cooling. The oil and gas then gradually enter the primary heat exchanger, secondary heat exchanger A, secondary heat exchanger B, tertiary heat exchanger A, and tertiary heat exchanger B for cooling in stages. The cooled low-temperature gas returns to the regenerative heat exchanger for reheating and then enters the subsequent treatment stage after meeting the standards. The condensed liquid oil is led to the oil collection tank. Low-concentration oil and gas can be directly discharged in compliance with standards or enter the next stage, such as an adsorption unit, an absorption unit, an oxidation catalytic unit, or a direct combustion unit, for further purification treatment of the oil and gas. The refrigeration system includes a primary refrigeration system, a secondary refrigeration system, and a tertiary refrigeration system. The primary refrigeration system operates continuously under high-temperature conditions to complete the initial cooling of oil and gas and ensure the economic operation of the system. The secondary and tertiary refrigeration systems perform deep cryogenic cooling on the oil and gas after primary refrigeration. The control system includes shut-off valves B, C, F, and G. The secondary heat exchanger A, the tertiary heat exchanger A, shut-off valves B and F are connected in series to form working channel A. Shut-off valve B is positioned between the outlet of the primary heat exchanger and the inlet of the secondary heat exchanger A, and shut-off valve F is positioned between the outlet of the tertiary heat exchanger and the cold-side inlet of the regenerating heat exchanger. When working channel A is unobstructed, it functions as a cooling oil-gas system. The secondary heat exchanger B, the tertiary heat exchanger B, shut-off valve C, and shut-off valve G are connected in series to form working channel B. Shut-off valve C is positioned between the outlet of the induced draft fan and the inlet of the secondary heat exchanger B, and shut-off valve G is positioned between the outlet of the tertiary heat exchanger B and the inlet of the buffer tank. When working channel B is frozen, it functions as a hot-melt oil-gas system.

[0006] Preferably, the primary refrigeration system includes a primary refrigeration compressor, a primary high-efficiency oil separator, a primary condenser, a primary throttling element, a primary gas-liquid separator, and a primary refrigeration compressor. The high-temperature, high-pressure refrigerant gas discharged from the primary refrigeration compressor is separated into oil by the primary high-efficiency oil separator and then enters the primary condenser to be condensed into high-pressure refrigerant liquid. The high-pressure refrigerant liquid is depressurized by the primary throttling element into a low-temperature, low-pressure vapor-liquid two-phase mixture and then enters the primary heat exchanger. The low-temperature, low-pressure vapor-liquid two-phase mixture evaporates in the primary heat exchanger and absorbs the heat from the oil and gas passing through it, thereby cooling and liquefying the oil and gas flowing through the primary heat exchanger. After the refrigerant is fully vaporized, it passes through the primary gas-liquid separator and is then compressed by the primary refrigeration compressor to enter the next cycle. Flame arresters can be installed before and after the induced draft fan. A liquid receiver and a dryer filter can be installed after the primary condenser 303 in the primary refrigeration system.

[0007] Preferably, the secondary refrigeration system includes a secondary refrigeration compressor, a secondary high-efficiency oil separator, a secondary condenser, an evaporative condenser throttling element, a secondary A throttling element, a secondary B throttling element, an evaporative condenser, and a three-in-one unit. The high-temperature, high-pressure refrigerant gas discharged from the secondary refrigeration compressor is separated into oil by the secondary high-efficiency oil separator and then enters the secondary condenser to be condensed into high-pressure refrigerant liquid. The high-pressure refrigerant liquid passes through the three-in-one unit and is divided into two paths, which are depressurized by the evaporative condenser throttling element, the secondary A throttling element, and the secondary B throttling element to form a low-temperature, low-pressure vapor-liquid two-phase mixture. The vapor-liquid two-phase mixture enters the evaporative condenser heat exchanger and the primary heat exchanger, respectively. The vapor-liquid two-phase mixture is condensed and vaporized in the evaporative condenser heat exchanger. The condensed and vaporized refrigerant is compressed by the secondary refrigeration compressor to enter the next cycle. Similarly, a dryer filter can be installed after the secondary condenser in the secondary refrigeration system.

[0008] Preferably, three heat exchange branches are constructed, including a first heat exchange branch, a second heat exchange branch, and a third heat exchange branch. The first heat exchange branch includes the evaporator-condenser throttling element and the evaporator-condenser. The second heat exchange branch includes the secondary A throttling element and the secondary heat exchanger A. The third heat exchange branch includes the secondary B throttling element and the secondary heat exchanger. The secondary refrigeration compressor, the secondary high-efficiency oil separator, the secondary condenser, the three parallel heat exchange branches, and the three-in-one unit are sequentially connected to form a secondary refrigeration cycle loop.

[0009] Preferably, the three-stage refrigeration system includes a three-stage refrigeration compressor, a three-stage high-efficiency oil separator, an evaporator-condenser, a three-stage A throttling element, a three-stage B throttling element, and a three-stage gas-liquid separator. The high-temperature, high-pressure refrigerant gas discharged from the third refrigeration compressor is separated into oil by the three-stage high-efficiency oil separator and then enters the evaporator-condenser heat exchanger to be condensed into high-pressure refrigerant liquid. The two-stage and three-stage refrigeration systems share the evaporator-condenser, forming a dual-machine cascade refrigeration system. The refrigerant liquid is further cooled by the three-stage gas-liquid separator. The cooled refrigerant is throttled and depressurized by the three-stage A throttling element and the three-stage B throttling element into a low-temperature, low-pressure vapor-liquid two-phase mixture, which then enters the three-stage heat exchanger A. The low-temperature, low-pressure vapor-liquid two-phase mixture evaporates in the three-stage heat exchanger A and absorbs the heat from the oil and gas passing through it, allowing the oil and gas flowing through the three-stage heat exchanger A to be further cooled and liquefied. After the refrigerant is fully vaporized, it passes through the three-stage gas-liquid separator and is then compressed by the three-stage refrigeration compressor to enter the next cycle. The three-stage refrigeration system may be equipped with a liquid receiver and a dryer filter after the evaporator-condenser 600.

[0010] Preferably, a fourth heat exchange branch and a fifth heat exchange branch are constructed. The fourth heat exchange branch includes the third-stage A throttling element and the third-stage heat exchanger A. The fifth heat exchange branch includes the third-stage B throttling element and the third-stage heat exchanger B. The three-stage refrigeration compressor, the three-stage high-efficiency oil separator, the evaporator-condenser, the parallel fourth and fifth heat exchange branches, and the third-stage gas-liquid separator are sequentially connected to form a three-stage refrigeration cycle loop. The three-stage heat exchange of the three-stage refrigeration system... Heat exchanger A and tertiary heat exchanger B are controlled by throttling elements of tertiary A and tertiary B respectively, alternating between cooling and standby. When the working channel of A is cooling the oil-gas system, the throttling element of tertiary A is turned on, and tertiary heat exchanger A is cooled; the throttling element of tertiary B is turned off, and tertiary heat exchanger B is in standby mode. When the working channel of B is cooling the oil-gas system, the throttling element of tertiary A is turned off, tertiary heat exchanger A is in standby mode, and the throttling element of tertiary B is turned on, and tertiary heat exchanger B is cooled.

[0011] Preferably, the control system further includes a pressure transmitter, shut-off valves A, D, E, and H, differential pressure transmitters A and B, and control elements. Shut-off valve A is located between the induced draft fan and the inlet of the secondary heat exchanger A; shut-off valve D is located between the outlet of the primary heat exchanger and the inlet of the secondary heat exchanger B; shut-off valve E is located between the outlet of the tertiary heat exchanger A and the inlet of the buffer tank; and shut-off valve H is located between the outlet of the tertiary heat exchanger B and the cold-side inlet of the regenerating heat exchanger. The pressure transmitter is installed at the inlet of the main oil and gas inlet pipe. At the location, the differential pressure transmission A is installed between the outlet of the secondary heat exchanger A and the inlet of the tertiary heat exchanger A, and the differential pressure transmission B is installed between the outlet of the secondary heat exchanger B and the inlet of the tertiary heat exchanger B. The outlets of the tertiary heat exchanger A and the tertiary heat exchanger B are respectively connected to the cold side gas inlet of the regenerating heat exchanger through the shut-off valve F and the shut-off valve H. The control element is used to control the opening and closing of the shut-off valves in the switching cooling oil-gas system and the hot melt oil-gas system. The differential pressure transmission A and the differential pressure transmission B measure the differential pressure value of the oil-gas passage and the running time of the cooling oil-gas system.

[0012] Preferably, when the A working channel is in the cooling oil and gas system operating state, the differential pressure transmitter A is lower than the preset value. The control element controls the opening of the shut-off valves B, F, D, and H, the secondary A throttling element opens, the secondary heat exchanger A cools down, the secondary B throttling element closes, the secondary heat exchanger B is in standby mode, the oil and gas are transported from the buffer tank to the regenerating heat exchanger by the induced draft fan for initial cooling of 10°C, then cooled to 2~6°C by the primary heat exchanger, then cooled to -30~-22°C by the shut-off valve B to the secondary heat exchanger A, then cooled to -80~-70°C by the tertiary heat exchanger A, and finally passed through the shut-off valve F. When the regenerative heat exchanger is heated to ambient temperature for discharge or introduction into the subsequent process, and the B working channel is a cooling oil-gas system, the secondary A throttling element is closed, the secondary heat exchanger A is in standby mode, the secondary B throttling element is open, and the secondary heat exchanger B cools down. When the B working channel is in the working state of a hot melt oil-gas system, the differential pressure transmitter B reaches the set value, and the control element controls the opening of the shut-off valves C, G, A, and E. The induced draft fan is frequency-increased by 10Hz, and approximately 20% more ambient temperature oil-gas flows through the shut-off valve C to the secondary heat exchanger B, then through the tertiary heat exchanger B, and finally back to the buffer tank through the shut-off valve G, forming a closed hot melt oil-gas system.

[0013] Preferably, the induced draft fan and the pressure transmitter are interlocked. The larger the value transmitted by the pressure transmitter, the higher the operating frequency of the induced draft fan and the larger the induced draft volume of the induced draft fan. After the value transmitted by the pressure transmitter is placed within a set range, the operating frequency of the induced draft fan tends to stabilize.

[0014] Beneficial Effects: The oil and gas recovery system disclosed in this invention addresses the unavoidable ice blockage phenomenon in the initial condensation process oil and gas recovery device, particularly in the secondary and tertiary heat exchangers. The cooling oil and gas system cools the oil and gas to the designed temperature, allowing for normal condensation and liquefaction. The hot melt oil and gas system melts the solid oil and gas blockage within the oil and gas channels. When ice blockage occurs in one of the oil and gas channels, the control element controls the opening and closing of the shut-off valve, thereby switching between working channels A and B. The original blocked channel is switched to the hot melt oil and gas system, using ambient temperature oil and gas for defrosting, clearing the channel for use. This meets the requirements for continuous operation of the oil and gas recovery facilities at the tanker terminal. By measuring the differential pressure value of the oil and gas channels and the operating time of the cooling oil and gas system using two differential pressure transmitters, a suitable oil and gas channel is selected to ensure the continuous operation of the device. The primary refrigeration system maintains operation in refrigeration mode with high stability. The hot melt oil-gas system adopts an oil-gas self-defrosting process to avoid sudden cooling and heating of heat exchange tubes, reduce the risk of heat exchanger leakage, and ensure long-term stable operation of the unit. The shut-off valve used in this system only acts on the oil-gas side, and conventional ball valves or butterfly valves can be selected, which are reliable and low in cost. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0016] In the attached diagram: Figure 1 This is a schematic diagram of the oil and gas system of the wharf oil and gas recovery system of the present invention; Figure 2 This is a schematic diagram of the primary refrigeration system of the wharf oil and gas recovery system of the present invention; Figure 3 This is a schematic diagram of the secondary and tertiary refrigeration systems of the wharf oil and gas recovery system of the present invention.

[0017] Labels in the diagram: 101, Buffer tank; 102, Exhaust fan; 103, Regenerative heat exchanger; 104, Primary heat exchanger; 105, Secondary heat exchanger A; 106, Secondary heat exchanger B; 107, Tertiary heat exchanger A; 108, Tertiary heat exchanger B; 200, Pressure transmitter; 201, Shut-off valve A; 202, Shut-off valve B; 203, Shut-off valve C; 204, Shut-off valve D; 205, Shut-off valve E; 206, Shut-off valve F; 207, Shut-off valve G; 208, Shut-off valve H; 209, Differential pressure transmitter A; 210, Differential pressure transmitter B; 211, Control element; 301, Primary stage. Refrigeration compressor; 302, First-stage high-efficiency oil separator; 303, First-stage condenser; 304, First-stage throttling element; 305, First-stage gas-liquid separator; 401, Second-stage refrigeration compressor; 402, Second-stage high-efficiency oil separator; 403, Second-stage condenser; 404, Evaporator-condenser throttling element; 405, Second-stage A throttling element; 406, Second-stage B throttling element; 407, Three-in-one unit; 501, Third-stage refrigeration compressor; 502, Third-stage high-efficiency oil separator; 503, Third-stage A throttling element; 504, Third-stage B throttling element; 505, Third-stage gas-liquid separator; 600, Evaporator-condenser. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following text is only used to describe an implementation of a terminal oil and gas recovery system of the present invention, and does not strictly limit the specific scope of protection claimed by the present invention.

[0019] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0020] Example 1: As Figures 1-3 As shown, this invention discloses a terminal oil and gas recovery system, comprising: Oil and gas systems, such as Figure 1As shown, the oil and gas system includes a buffer tank 101, an induced draft fan 102, a regenerating heat exchanger 103, a primary heat exchanger 104, a secondary heat exchanger A105, a secondary heat exchanger B106, a tertiary heat exchanger A107, and a tertiary heat exchanger B108. After being buffered and stabilized by the buffer tank 101, the oil and gas are sent by the induced draft fan 102 into the regenerating heat exchanger 103 for initial cooling. The oil and gas then gradually enter the primary heat exchanger 104, the secondary heat exchanger B106, and the tertiary heat exchanger B108. Heat exchanger A105, secondary heat exchanger B106, tertiary heat exchanger A107, and tertiary heat exchanger B108 are used to cool down the gas in stages. The cooled low-temperature gas is returned to the regenerating heat exchanger 103 for reheating and then enters the subsequent treatment stage after meeting the standards. The condensed liquid oil is led to the oil collection tank. Low-concentration oil and gas can be directly discharged in compliance with standards or enter the next stage, such as the adsorption unit, absorption unit, oxidation catalysis unit, or direct combustion unit, for further purification of the oil and gas. Refrigeration systems, such as Figure 2 and Figure 3 As shown, the refrigeration system includes a primary refrigeration system, a secondary refrigeration system, and a tertiary refrigeration system. The primary refrigeration system operates continuously under high-temperature conditions to complete the initial cooling of oil and gas and ensure the economic operation of the system. The secondary refrigeration system and the tertiary refrigeration system perform deep low-temperature refrigeration on the oil and gas after primary refrigeration. Control systems, such as Figure 1 As shown, the control system includes shut-off valves B202, C203, F206, and G207. The secondary heat exchanger A105, the tertiary heat exchanger A107, and shut-off valves B202 and F206 are connected in series to form working channel A. Shut-off valve B202 is positioned between the outlet of the primary heat exchanger 104 and the inlet of the secondary heat exchanger A105. Shut-off valve F206 is positioned between the outlet of the tertiary heat exchanger and the cold side of the regenerating heat exchanger 103. Between the inlets, when the A working channel is unobstructed, it is a cooling oil and gas system. The secondary heat exchanger B106, the tertiary heat exchanger B108, the shut-off valve C203, and the shut-off valve G207 are connected in series to form the B working channel. The shut-off valve C203 is placed between the outlet of the induced draft fan 102 and the inlet of the secondary heat exchanger B106, and the shut-off valve G207 is placed between the outlet of the tertiary heat exchanger B108 and the inlet of the buffer tank 101. When the B working channel is frozen, it is a hot melt oil and gas system.

[0021] In Example 1, as Figure 2As shown, the primary refrigeration system includes a primary refrigeration compressor 301, a primary high-efficiency oil separator 302, a primary condenser 303, a primary throttling element 304, and a primary gas-liquid separator 305. The high-temperature, high-pressure refrigerant gas discharged from the primary refrigeration compressor 301 is separated into oil by the primary high-efficiency oil separator 302 and then condensed into high-pressure refrigerant liquid by the primary condenser 303. The high-pressure refrigerant liquid is then depressurized by the primary throttling element 304 into a low-temperature, low-pressure vapor-liquid two-phase mixture. After the mixture enters the first-stage heat exchanger 104, the low-temperature and low-pressure vapor-liquid two-phase mixture evaporates in the first-stage heat exchanger 104 and absorbs the heat of the oil and gas passing through it, so that the oil and gas flowing through the first-stage heat exchanger 104 can be cooled and liquefied. After the refrigerant is fully vaporized, it passes through the first-stage gas-liquid separator 305 and is then compressed by the first-stage refrigeration compressor 301 to enter the next cycle. Flame arresters can be installed before and after the induced draft fan 102. The first-stage refrigeration system can be equipped with a liquid receiver and a dryer filter after the first-stage condenser 303.

[0022] In Example 1, as Figure 3 As shown, the secondary refrigeration system includes a secondary refrigeration compressor 401, a secondary high-efficiency oil separator 402, a secondary condenser 403, an evaporator-condenser throttling element 404, a secondary A throttling element 405, a secondary B throttling element 406, an evaporator-condenser 600, and a three-in-one unit 407. The high-temperature, high-pressure refrigerant gas discharged from the secondary refrigeration compressor 401 is separated into oil by the secondary high-efficiency oil separator 402 and then enters the secondary condenser 403 where it is condensed into high-pressure refrigerant liquid. The high-pressure refrigerant liquid then passes through the three-in-one unit 407. After the body 407, the refrigerant is divided into two paths and depressurized into a low-temperature, low-pressure vapor-liquid two-phase mixture through the evaporative condenser throttling element 404, the secondary A throttling element 405, and the secondary B throttling element 406. The vapor-liquid two-phase mixture enters the evaporative condenser heat exchanger and the primary heat exchanger 104, respectively. The vapor-liquid two-phase mixture is condensed and vaporized in the evaporative condenser heat exchanger. The condensed and vaporized refrigerant is compressed by the secondary refrigeration compressor 401 and enters the next cycle. Similarly, a dryer filter can be installed after the secondary condenser 403 in the secondary refrigeration system.

[0023] In Example 1, as Figure 3 As shown, three heat exchange branches are constructed, including a first heat exchange branch, a second heat exchange branch, and a third heat exchange branch. The first heat exchange branch includes the evaporator-condenser throttling element 404 and the evaporator-condenser 600. The second heat exchange branch includes the secondary A throttling element 405 and the secondary heat exchanger A105. The third heat exchange branch includes the secondary B throttling element 406 and the secondary heat exchanger. The secondary refrigeration compressor 401, the secondary high-efficiency oil separator 402, the secondary condenser 403, the three parallel heat exchange branches, and the three-in-one device 407 are sequentially connected to form a secondary refrigeration cycle loop.

[0024] In Example 1, as Figure 3 As shown, the three-stage refrigeration system includes a three-stage refrigeration compressor 501, a three-stage high-efficiency oil separator 502, an evaporator-condenser 600, a three-stage A throttling element 503, a three-stage B throttling element 504, and a three-stage gas-liquid separator 505. The high-temperature, high-pressure refrigerant gas discharged from the third refrigeration compressor is separated into oil by the three-stage high-efficiency oil separator 502 and then enters the evaporator-condenser heat exchanger to be condensed into high-pressure refrigerant liquid. The two-stage and three-stage refrigeration systems share the evaporator-condenser 600, forming a dual-machine cascade refrigeration system. The refrigerant liquid is further cooled by the three-stage gas-liquid separator 505. The cooled refrigerant is throttled and depressurized by the three-stage A throttling element 503 and the three-stage B throttling element 504 into a low-temperature, low-pressure vapor-liquid two-phase mixture, which then enters the three-stage heat exchanger A107. The low-temperature, low-pressure vapor-liquid two-phase mixture evaporates in the three-stage heat exchanger A107 and absorbs the heat from the oil and gas passing through it, allowing the oil and gas flowing through the three-stage heat exchanger A107 to be further cooled and liquefied. After the refrigerant is fully vaporized, it passes through the three-stage gas-liquid separator 505 and is then compressed by the three-stage refrigeration compressor 501 to enter the next cycle. The three-stage refrigeration system may be equipped with a liquid receiver and a dryer filter after the evaporator-condenser 600.

[0025] In Example 1, as Figure 3 As shown, a fourth heat exchange branch and a fifth heat exchange branch are constructed. The fourth heat exchange branch includes the third-stage A throttling element 503 and the third-stage heat exchanger A107. The fifth heat exchange branch includes the third-stage B throttling element 504 and the third-stage heat exchanger B108. The third-stage refrigeration compressor 501, the third-stage high-efficiency oil separator 502, the evaporator-condenser 600, the parallel fourth and fifth heat exchange branches, and the third-stage gas-liquid separator 505 are sequentially connected to form a three-stage refrigeration cycle loop. The third-stage heat exchanger A107 and the third-stage heat exchanger B108 of the three-stage refrigeration system are connected in sequence. The three-stage heat exchanger B108 is controlled by the three-stage A throttling element 503 and the three-stage B throttling element 504 to alternately cool down and standby. When the A working channel is cooling the oil and gas system, the three-stage A throttling element 503 turns on the three-stage heat exchanger A107 to cool down, and the three-stage B throttling element 504 turns off the three-stage heat exchanger B108 to standby. When the B working channel is cooling the oil and gas system, the three-stage A throttling element 503 turns off, the three-stage heat exchanger A107 stands by, and the three-stage B throttling element 504 turns on, and the three-stage heat exchanger B108 cools down.

[0026] Example 2: Figure 1As shown, the control system also includes a pressure transmitter 200, shut-off valves A201, D204, E205, and H208, differential pressure transmitters A209 and B210, and a control element 211. Shut-off valve A201 is located between the induced draft fan 102 and the inlet of the secondary heat exchanger A105; shut-off valve D204 is located between the outlet of the primary heat exchanger 104 and the inlet of the secondary heat exchanger B106; shut-off valve E205 is located between the outlet of the tertiary heat exchanger A107 and the inlet of the buffer tank 101; and shut-off valve H208 is located between the outlet of the tertiary heat exchanger B108 and the regenerator heat exchanger 101. Between the cold side inlets of 03, the pressure transmitter 200 is installed at the inlet of the main oil and gas inlet pipe, the differential pressure transmission A209 is installed between the outlet of the secondary heat exchanger A105 and the inlet of the tertiary heat exchanger A107, the differential pressure transmission B210 is installed between the outlet of the secondary heat exchanger B106 and the inlet of the tertiary heat exchanger B108, the outlets of the tertiary heat exchanger A107 and the tertiary heat exchanger B108 are respectively connected to the cold side gas inlet of the regenerating heat exchanger 103 through the shut-off valve F206 and the shut-off valve H208, and the control element 211 is used to control the opening and closing of the shut-off valves in the switching cooling oil and gas system and the hot melting oil and gas system.

[0027] In Example 2, as Figure 1 As shown, the induced draft fan 102 and the pressure transmitter 200 are interlocked. The larger the value transmitted by the pressure transmitter 200, the higher the operating frequency of the induced draft fan 102 and the larger the induced draft volume of the induced draft fan 102. After the value transmitted by the pressure transmitter 200 is placed within the set range, the operating frequency of the induced draft fan 102 tends to stabilize.

[0028] Example 3: Comparison of a traditional single-stage compressor-controlled dual-channel cooling system with the oil and gas recovery system provided by this invention for an oil and gas processing capacity of 300m³ 3 Oil and gas recovery is carried out at the wharf at a rate of / h, where the oil and gas consists of volatile oil and gas from refined oil products, and the inlet concentration of the oil and gas is 1000g / m³. 3 The traditional single-stage compressor-controlled dual-circuit cooling system for port oil and gas recovery units has a unit power of 70.8 kW and a unit energy consumption of 0.236 kW / (m³). 3 / h).

[0029] In Example 3, the oil and gas recovery system provided by the present invention was used to process 300m³ of oil and gas. 3The system recovers oil and gas at the / h terminal. The induced draft fan 102 is a 7.5kW explosion-proof Roots induced draft fan. The primary refrigeration compressor 301 is a 3.3kW explosion-proof scroll compressor ZB29KQE. The secondary refrigeration compressor 401 is a 40.1kW explosion-proof screw compressor RC2-180B. The tertiary refrigeration compressor 501 is a 12.0kW explosion-proof piston compressor 4GE-23Y. The air-cooled heat exchanger uses a 4.0kW axial flow fan. The unit energy consumption is 0.224kW / (m³). 3 The system ( / h) improves energy efficiency by 5.1% compared to traditional single-stage compressor control of dual-channel cooling field.

[0030] When this oil and gas recovery system is in use, if ice blockage occurs in one of the oil and gas channels, the control element 211 controls the opening and closing of the shut-off valve to switch between working channels A and B. The original ice-blocked channel switches to the hot-melt oil and gas system, using room-temperature oil and gas for defrosting, thereby meeting the requirements for continuous operation of the oil and gas recovery facilities at the tanker terminal. In embodiment two, when working channel A is in the cooling oil and gas system operating state, the differential pressure transmitter A209 is lower than the preset value. The control element 211 controls the shut-off valves B202, F206, D204, and H208 to open, and the secondary A section... When flow element 405 is turned on, the secondary heat exchanger A105 cools down, and the secondary B throttling element 406 is turned off, putting the secondary heat exchanger B106 into standby mode. Oil and gas are transported via the buffer tank 101 and the induced draft fan 102 to the regenerating heat exchanger 103 for initial cooling of 10°C. After passing through the primary heat exchanger 104, the temperature drops to 2-6°C. Then, through the shut-off valve B202, the temperature drops to -30 to -22°C in the secondary heat exchanger A105, and then further cools to -80 to -70°C in the tertiary heat exchanger A107. Finally, through the shut-off valve F206, the temperature rises to ambient temperature in the regenerating heat exchanger 103 before being discharged or introduced. In the first-stage process, when the B working channel is a cooling oil-gas system, the second-stage A throttling element 405 is closed, the second-stage heat exchanger A105 is in standby mode, the second-stage B throttling element 406 is open, and the second-stage heat exchanger B106 cools down. When the B working channel is in the hot melt oil-gas system operating state, the differential pressure transmitter B210 reaches the set value, and the control element 211 controls the opening of the shut-off valves C203, G207, A201, and E205. The induced draft fan 102 increases its frequency by 10Hz, and approximately 20% more ambient temperature oil-gas passes through the shut-off valve C203 to the second-stage heat exchanger. B106, then through the third-stage heat exchanger B108, and then through the shut-off valve G207 back to the buffer tank 101, forming a closed-loop hot melt oil-gas system. The differential pressure value of the oil-gas channel and the running time of the cooling oil-gas system are measured by two differential pressure transmitters to select a suitable oil-gas channel, ensuring the continuity of the unit's operation. The primary refrigeration system maintains the refrigeration mode, which is highly stable. The hot melt oil-gas system adopts an oil-gas self-defrosting process to avoid sudden cooling and heating of the heat exchange tubes, reduce the risk of heat exchanger leakage, and ensure the long-term stable operation of the unit. The shut-off valve used in this system only acts on the oil-gas side, and conventional ball valves or butterfly valves can be selected, which are reliable and low in cost.

[0031] The above description only describes the present invention and its embodiments. This description is not restrictive. Those skilled in the art will realize that the embodiments described herein are to help readers understand the principles of the present invention and should be understood as not limiting the scope of protection of the present invention to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations without departing from the essence of the present invention based on the technical teachings disclosed in the present invention, and these modifications and combinations are still within the scope of protection of the present invention.

Claims

1. A port oil and gas recovery system, characterized in that, include: The oil and gas system includes a buffer tank, an induced draft fan, a regenerating heat exchanger, a primary heat exchanger, a secondary heat exchanger A, a secondary heat exchanger B, a tertiary heat exchanger A, and a tertiary heat exchanger B. After the oil and gas are buffered and stabilized by the buffer tank, they are sent into the regenerating heat exchanger by the induced draft fan for initial cooling. The oil and gas then gradually enter the primary heat exchanger, secondary heat exchanger A, secondary heat exchanger B, tertiary heat exchanger A, and tertiary heat exchanger B for cooling in stages. The cooled low-temperature gas returns to the regenerating heat exchanger for reheating before entering the subsequent processing stage. The refrigeration system includes a primary refrigeration system, a secondary refrigeration system, and a tertiary refrigeration system. The primary refrigeration system operates continuously under high-temperature conditions to complete the initial cooling of oil and gas and ensure the economic operation of the system. The secondary and tertiary refrigeration systems perform deep cryogenic cooling on the oil and gas after primary refrigeration. The control system includes shut-off valves B, C, F, and G. The secondary heat exchanger A, the tertiary heat exchanger A, shut-off valves B and F are connected in series to form working channel A. Shut-off valve B is positioned between the outlet of the primary heat exchanger and the inlet of the secondary heat exchanger A, and shut-off valve F is positioned between the outlet of the tertiary heat exchanger and the cold-side inlet of the regenerating heat exchanger. When working channel A is unobstructed, it functions as a cooling oil-gas system. The secondary heat exchanger B, the tertiary heat exchanger B, shut-off valve C, and shut-off valve G are connected in series to form working channel B. Shut-off valve C is positioned between the outlet of the induced draft fan and the inlet of the secondary heat exchanger B, and shut-off valve G is positioned between the outlet of the tertiary heat exchanger B and the inlet of the buffer tank. When working channel B is frozen, it functions as a hot-melt oil-gas system.

2. The terminal oil and gas recovery system according to claim 1, characterized in that: The primary refrigeration system includes a primary refrigeration compressor, a primary high-efficiency oil separator, a primary condenser, a primary throttling element, and a primary gas-liquid separator. The high-temperature, high-pressure refrigerant gas discharged from the primary refrigeration compressor is separated into oil by the primary high-efficiency oil separator and then enters the primary condenser to be condensed into high-pressure refrigerant liquid. The high-pressure refrigerant liquid is depressurized by the primary throttling element into a low-temperature, low-pressure vapor-liquid two-phase mixture and then enters the primary heat exchanger. The low-temperature, low-pressure vapor-liquid two-phase mixture evaporates in the primary heat exchanger and absorbs the heat from the oil and gas passing through it, thereby cooling and liquefying the oil and gas flowing through the primary heat exchanger. After the refrigerant is fully vaporized, it is compressed again by the primary refrigeration compressor through the primary gas-liquid separator to enter the next cycle.

3. The terminal oil and gas recovery system according to claim 1, characterized in that: The secondary refrigeration system includes a secondary refrigeration compressor, a secondary high-efficiency oil separator, a secondary condenser, an evaporative condenser throttling element, a secondary A throttling element, a secondary B throttling element, an evaporative condenser, and a three-in-one unit. The high-temperature, high-pressure refrigerant gas discharged from the secondary refrigeration compressor is separated into oil by the secondary high-efficiency oil separator and then enters the secondary condenser to be condensed into high-pressure refrigerant liquid. The high-pressure refrigerant liquid passes through the three-in-one unit and is divided into two paths, which are depressurized by the evaporative condenser throttling element, the secondary A throttling element, and the secondary B throttling element to form a low-temperature, low-pressure vapor-liquid two-phase mixture. The vapor-liquid two-phase mixture enters the evaporative condenser heat exchanger and the primary heat exchanger, respectively. The vapor-liquid two-phase mixture is condensed and vaporized in the evaporative condenser heat exchanger, and the condensed and vaporized refrigerant is compressed by the secondary refrigeration compressor to enter the next cycle.

4. The terminal oil and gas recovery system according to claim 3, characterized in that: Three heat exchange branches are constructed, including a first heat exchange branch, a second heat exchange branch, and a third heat exchange branch. The first heat exchange branch includes the evaporator-condenser throttling element and the evaporator-condenser. The second heat exchange branch includes the secondary A throttling element and the secondary heat exchanger A. The third heat exchange branch includes the secondary B throttling element and the secondary heat exchanger. The secondary refrigeration compressor, the secondary high-efficiency oil separator, the secondary condenser, the three parallel heat exchange branches, and the three-in-one unit are sequentially connected to form a secondary refrigeration cycle loop.

5. The terminal oil and gas recovery system according to claim 3, characterized in that: The three-stage refrigeration system includes a three-stage refrigeration compressor, a three-stage high-efficiency oil separator, an evaporator-condenser, a three-stage A throttling element, a three-stage B throttling element, and a three-stage gas-liquid separator. The high-temperature, high-pressure refrigerant gas discharged from the third refrigeration compressor is separated into oil by the three-stage high-efficiency oil separator and then enters the evaporator-condenser heat exchanger to be condensed into high-pressure refrigerant liquid. The two-stage and three-stage refrigeration systems share the evaporator-condenser, forming a dual-machine cascade refrigeration system. The refrigerant liquid is further cooled by the three-stage gas-liquid separator. The cooled refrigerant is then throttled and depressurized by the three-stage A and B throttling elements to become a low-temperature, low-pressure vapor-liquid two-phase mixture, which enters the three-stage heat exchanger A. The low-temperature, low-pressure vapor-liquid two-phase mixture evaporates in the three-stage heat exchanger A and absorbs the heat from the oil and gas passing through it, further cooling and liquefying the oil and gas flowing through the three-stage heat exchanger A. After the refrigerant is fully vaporized, it is compressed again by the three-stage refrigeration compressor through the three-stage gas-liquid separator to enter the next cycle.

6. The terminal oil and gas recovery system according to claim 5, characterized in that: A fourth and fifth heat exchange branch are constructed. The fourth heat exchange branch includes the third-stage A throttling element and the third-stage heat exchanger A. The fifth heat exchange branch includes the third-stage B throttling element and the third-stage heat exchanger B. The three-stage refrigeration compressor, the three-stage high-efficiency oil separator, the evaporator-condenser, the parallel fourth and fifth heat exchange branches, and the third-stage gas-liquid separator are sequentially connected to form a three-stage refrigeration cycle loop. The third-stage heat exchanger A of the three-stage refrigeration system... The three-stage heat exchanger B is controlled by the three-stage A throttling element and the three-stage B throttling element respectively, alternating between cooling and standby. When the working channel of A is cooling the oil and gas system, the three-stage A throttling element is turned on, and the three-stage B throttling element is turned off, and the three-stage heat exchanger B is in standby mode. When the working channel of B is cooling the oil and gas system, the three-stage A throttling element is turned off, the three-stage heat exchanger A is in standby mode, and the three-stage B throttling element is turned on, and the three-stage heat exchanger B is cooling.

7. The terminal oil and gas recovery system according to claim 6, characterized in that: The control system also includes a pressure transmitter, shut-off valves A, D, E, and H, differential pressure transmitters A and B, and control elements. Shut-off valve A is located between the induced draft fan and the inlet of the secondary heat exchanger A; shut-off valve D is located between the outlet of the primary heat exchanger and the inlet of the secondary heat exchanger B; shut-off valve E is located between the outlet of the tertiary heat exchanger A and the inlet of the buffer tank; and shut-off valve H is located between the outlet of the tertiary heat exchanger B and the cold-side inlet of the regenerating heat exchanger. The force transmitter is installed at the inlet of the main oil and gas inlet pipe. The differential pressure transmission A is installed between the outlet of the secondary heat exchanger A and the inlet of the tertiary heat exchanger A. The differential pressure transmission B is installed between the outlet of the secondary heat exchanger B and the inlet of the tertiary heat exchanger B. The outlets of the tertiary heat exchanger A and the tertiary heat exchanger B are respectively connected to the cold side gas inlet of the regenerating heat exchanger through the shut-off valve F and the shut-off valve H. The control element is used to control the opening and closing of the shut-off valves in the switching cooling oil and gas system and the hot melt oil and gas system.

8. The terminal oil and gas recovery system according to claim 7, characterized in that: When the A working channel is in the cooling oil-gas system operating state, the differential pressure transmitter A is below the preset value. The control element controls the shut-off valves B, F, D, and H to open, the secondary A throttling element to open, the secondary heat exchanger A to cool down, the secondary B throttling element to close, and the secondary heat exchanger B to standby. When the B working channel is in the cooling oil-gas system operating state, the secondary A throttling element to close, the secondary heat exchanger A to standby, the secondary B throttling element to open, and the secondary heat exchanger B to cool down. When the B working channel is in the hot melt oil-gas system operating state, the differential pressure transmitter B reaches the set value, and the shut-off valves C, G, A, and E open.

9. A terminal oil and gas recovery system according to claim 7, characterized in that: The induced draft fan and the pressure transmitter are interlocked. The higher the value transmitted by the pressure transmitter, the higher the operating frequency of the induced draft fan and the greater the induced draft volume. After the value transmitted by the pressure transmitter is within a set range, the operating frequency of the induced draft fan tends to stabilize.

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