Storage tank oil gas suppression and recovery device and method based on radiation refrigeration and multi-stage cold trap

Abstract

The invention relates to a storage tank oil gas restraining and recycling device and method based on radiation refrigeration and a multi-stage cold trap, and belongs to the technical field of oil gas storage and transportation and energy conservation and environmental protection. The device is arranged at the exhaust end of a breather valve of the storage tank and comprises a heat insulation gas collection cavity, a radiation refrigeration condensation module, a backflow liquid guide mechanism and a source inhibition pre-cooling loop. A spectrum selective radiation refrigeration layer is arranged on the outer surface of the radiation refrigeration condensation module, and condensation fins are arranged on the inner surface; the condensation fins are provided with macroscopic turbulent flow units and microcosmic liquid guide channels and used for prolonging the oil gas residence time, breaking a thermal boundary layer and accelerating condensate self-expelling. The source inhibition pre-cooling loop introduces gas at the top of the storage tank into a heat insulation gas collection cavity through natural heat convection at the initial temperature rise stage of the storage tank, pre-cools the gas and then flows back, and the breathing emission is reduced from the source. The method has the advantages that zero-energy-consumption operation is achieved in the whole process, the dual functions of source inhibition and efficient recovery are achieved, and a safe and economical solution is provided for treatment of VOCs in the distributed storage tank.

Description

Technical Field

[0001] This invention relates to a storage tank oil and gas suppression and recovery device and method based on radiation refrigeration and multi-stage cold traps, belonging to the field of petrochemical environmental protection equipment technology. Background Technology

[0002] In the petrochemical industry, crude oil and refined oil storage tanks experience changes in temperature and pressure of gases during storage due to diurnal temperature variations and solar radiation. During the day, as temperatures rise, the oil and gas inside the tank expand and increase in pressure, releasing into the atmosphere through a breather valve, creating a "breathing" process (small breathing loss). This released gas is rich in high concentrations of volatile organic compounds (VOCs), causing not only significant resource waste but also being a major source of air pollution (such as PM2.5 and ozone precursors).

[0003] Current vapor recovery unit (VRU) technologies mainly include adsorption, absorption, membrane separation, and condensation. However, these traditional technologies mostly fall under the category of "end-of-pipe active treatment" and have the following problems:

[0004] 1. High energy consumption: It requires a compressor, refrigeration unit or vacuum pump, resulting in high power consumption.

[0005] 2. High investment and maintenance costs: Large footprint, complex equipment, and high maintenance frequency.

[0006] 3. Limited applicability: For remote areas, offshore platforms, or scattered individual storage tanks, the above-mentioned active recovery technology is difficult to implement due to the lack of power supply or the difficulty in laying a centralized recovery pipeline network.

[0007] In recent years, radiative cooling technology has attracted much attention as an emerging zero-energy refrigeration method. Its principle is to directly emit heat into the cold outer space in the form of infrared radiation through an atmospheric window (8-13 μm), while reflecting most of the sunlight, thus achieving a cooling effect below ambient temperature even under sunlight. However, directly applying radiative cooling to oil and gas condensation still faces two major technical bottlenecks: first, light components have low dew points, limiting the efficiency of conventional condensation under natural temperature differences; second, the liquid film formed during condensation adheres to the heat exchange surface, significantly increasing thermal resistance and hindering subsequent condensation. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies, the present invention aims to provide a storage tank oil and gas suppression and recovery device and method based on radiation refrigeration and multi-stage cold traps. It utilizes space as a natural cold source and combines superoleophobic interface technology to propose a dual intervention mechanism of source suppression (prevention) and enhanced condensation (treatment). It can achieve efficient condensation and recovery of oil and gas discharged from storage tanks without the need for electric drive.

[0009] This invention provides a storage tank oil and gas suppression and recovery device and method based on radiation refrigeration and multi-stage cold traps. The technical solution of this invention is as follows:

[0010] A storage tank oil and gas suppression and recovery device based on radiative cooling and multi-stage cold traps, comprising:

[0011] The insulated gas collection chamber (1) has an air inlet (11) and a drain outlet (12) at its bottom. The air inlet (11) is used to connect with the breather valve of the storage tank.

[0012] The radiation cooling condensation module (2) is airtightly covered at the top opening of the heat-insulating gas collection chamber (1) and is used to condense the oil-gas mixture entering the heat-insulating gas collection chamber (1) by means of passive radiation cooling.

[0013] A reflux guiding mechanism (3), connected to the drain port (12), is used to guide the condensed liquid unidirectionally back into the storage tank; and

[0014] The source suppression pre-cooling circuit (6) connects the insulated gas collection chamber (1) with the top gas phase space of the storage tank. It is used to introduce the gas in the storage tank into the insulated gas collection chamber (1) for pre-cooling and return to the storage tank by means of natural heat convection before the breathing valve of the storage tank is opened.

[0015] The radiation cooling condensation module (2) includes a high thermal conductivity substrate (21), which has a side facing the external sky and a side facing the interior of the adiabatic gas collection cavity (1). The side of the high thermal conductivity substrate (21) facing the sky is provided with a spectrally selective radiation cooling layer (22), which is used to radiate heat into space. The side of the high thermal conductivity substrate (21) facing the interior of the adiabatic gas collection cavity is provided with a number of condensation fins (23), which are used to exchange heat with the oil and gas in the cavity. The condensation fins (23) are provided with condensation enhancement components. The condensation enhancement components are a macroscopic turbulence unit and a microscopic liquid guiding channel. The macroscopic turbulence unit is used to prolong the residence time of oil and gas on the cold surface and induce gas to form turbulence, so as to destroy the gas thermal boundary layer. The microscopic liquid guiding channel is used to accelerate the self-displacement of condensed droplets through capillary action and gravity, so as to realize the renewal of the condensation surface.

[0016] The macroscopic turbulence unit includes louvered slits or stamped flow guides staggered on the surface of the condenser fins (23); the stamped flow guides on adjacent fins are staggered to form an S-shaped or spiral turbulent flow field for the oil-gas mixture flowing through.

[0017] The micro-fluid guiding channel includes a micron-scale trench array extending along the direction of gravity on the surface of the fin substrate; both the trench array and the fin surface are covered with a superoleophobic micro / nano composite coating; the superoleophobic micro / nano composite coating has a contact angle greater than 150° and a roll-off angle less than 10° for alkane liquids with a surface tension greater than 20 mN / m.

[0018] The source suppression precooling circuit (6) includes an ascending gas pipe (61) and a descending liquid-gas mixing pipe (62); one end of the ascending gas pipe (61) is connected to the highest point of the top of the storage tank and communicates with the storage tank, and the other end is connected to the upper part of the insulated gas collection chamber (1); one end of the descending liquid-gas mixing pipe (62) is connected to the bottom liquid collection area of ​​the insulated gas collection chamber (1), and the other end extends into the inside of the storage tank; under thermal convection conditions, the gas at the top of the storage tank enters the insulated gas collection chamber (1) through the ascending gas pipe (61), and after being cooled, carries the condensate back to the storage tank through the descending liquid-gas mixing pipe (62), forming a thermosiphon natural convection circulation.

[0019] The source suppression precooling circuit (6) is equipped with a differential pressure balancing valve (63) on the rising gas pipe (61). When the pressure inside the storage tank is lower than the opening pressure of the breather valve and there is thermal convection, the differential pressure balancing valve (63) is normally open, allowing the gas at the top of the storage tank to enter the insulated gas collection chamber (1) through the rising gas pipe (61) for precooling and reflux. When the pressure inside the storage tank reaches the setting pressure of the breather valve, the differential pressure balancing valve (63) is closed, and the waste gas from the storage tank enters the insulated gas collection chamber (1) through the air inlet (11) for centralized condensation.

[0020] It also includes a thermal diode assembly (5), which is embedded at the connection between the radiative cooling condensing module (2) and the adiabatic gas collection chamber (1) to allow heat to be conducted unidirectionally from the adiabatic gas collection chamber (1) to the radiative cooling condensing module (2).

[0021] The radiant cooling condensing module (2) is generally arranged in the shape of an inverted frustum or a funnel. The condensing fins (23) are radially distributed along the conical surface, and the bottom of the fins is inclined towards the center of the adiabatic gas collection chamber (1). The reflux liquid guiding mechanism (3) includes a liquid collection funnel (31) and a U-shaped liquid seal pipe (32). The liquid collection funnel (31) is located at the drain port (12), and the U-shaped liquid seal pipe (32) is connected to the bottom of the liquid collection funnel (31). A safety bypass valve (4) is also provided on the side wall of the adiabatic gas collection chamber (1). The opening pressure setting value of the safety bypass valve (4) is higher than the opening pressure of the tank breather valve.

[0022] The spectrally selective radiation cooling layer (22) has a solar reflectivity greater than 0.95 in the 0.3-2.5 μm band and a thermal emissivity greater than 0.90 in the 8-13 μm band.

[0023] A recovery method for a storage tank oil and gas suppression and recovery device based on radiative cooling and a multi-stage cold trap includes the following steps:

[0024] Source suppression step: When the pressure inside the storage tank is lower than the set pressure for opening the breather valve and there is thermal convection, the differential pressure balance valve (63) opens. Under the action of natural thermal convection, the gas in the gas phase space at the top of the storage tank enters the upper part of the insulated gas collection chamber (1) through the rising gas pipe (61) and exchanges heat with the radiant cooling condensing module (2). After the gas is cooled, the density increases and carries some condensate back to the inside of the storage tank through the descending liquid-gas mixing pipe (62), forming a thermosiphon natural convection circulation to suppress the pressure rise inside the storage tank. Centralized condensation and recovery step: When the pressure inside the storage tank reaches the set pressure for opening the breather valve, the differential pressure balance valve (63) closes and the storage tank breather valve opens. The oil-gas mixture discharged from the storage tank enters the insulated gas collection chamber (1) through the air inlet (11). The oil-gas mixture is cooled on the surface of the condensing fins (23) of the radiant cooling condensing module (2), where the condensable components are condensed into liquid. The condensate is guided back to the inside of the storage tank in one direction through the return liquid guiding mechanism (3). In the centralized condensation and recovery step, when the oil-gas mixture flows through the condensation fins (23), it is subjected to macroscopic turbulence units to form turbulence, thereby destroying the thermal boundary layer. The condensed droplets are self-driven away from the fin surface under the synergistic effect of the microscopic liquid guiding channels and the superoleophobic surface, thus achieving the renewal of the condensation surface.

[0025] The advantages of this invention are: no electric drive throughout the entire process, no moving mechanical parts, eliminating the risk of electrical sparks, making it particularly suitable for flammable and explosive oil and gas environments. Utilizing radiative cooling technology, it not only provides significant effects at night but also overcomes solar radiation during the day to achieve sub-ambient temperature cooling, covering the main period of "small breathing" in storage tanks (daytime warming phase). Introducing a preventative thermosiphon pre-cooling concept, it pre-digests the thermal expansion energy within the tank before the breather valve actuates, reducing emissions at the source; combined with efficient condensation during exhaust gas discharge, the overall emission reduction and recovery rate significantly surpasses that of single passive condensation devices. Through the synergistic effect of the finned macroscopic flow channel turbulence design (delay, turbulence enhancement) and the microscopic superhydrophobic guiding grooves, it breaks through the liquid film thermal resistance limitation of traditional phase change heat transfer, achieving efficient "stripping" and liquefaction of lightweight VOCs components even under limited natural temperature differences. It can be directly installed as a "cap" on existing storage tank breather valves without the need for laying pipelines and cables, resulting in extremely low modification costs. Attached Figure Description

[0026] Figure 1 This is a cross-sectional view of the main structure of the device of the present invention.

[0027] Figure 2 yes Figure 1 Schematic diagram of macroscopic turbulence and microscopic liquid guiding structure of the medium-radiation refrigeration condensation module.

[0028] Figure 3 This is a schematic diagram of the heat flow and material flow principle of the device of the present invention during daytime operation.

[0029] Figure 4 Comparative analysis chart of oil and gas recovery data from embodiments of the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0031] See Figures 1 to 4 This invention relates to a storage tank oil and gas suppression and recovery device based on radiative cooling and multi-stage cold traps, comprising:

[0032] The heat-insulating gas collection chamber 1 has an air inlet 11 and a liquid outlet 12 at its bottom. The air inlet 11 is used to connect with the breather valve of the storage tank.

[0033] The radiative cooling condensation module 2 is airtightly covered at the top opening of the insulated gas collection chamber 1, and is used to condense the oil-gas mixture entering the insulated gas collection chamber 1 by means of passive radiative cooling.

[0034] The reflux guiding mechanism 3, connected to the drain port 12, is used to guide the condensed liquid back into the storage tank in a one-way manner; the reflux guiding mechanism 3 is located at the lowest point of the bottom of the insulated gas collection chamber, and guides the collected liquid oil back into the storage tank through a one-way valve or a U-shaped liquid seal structure, while preventing backflow of outside air; and

[0035] The source suppression pre-cooling circuit 6 connects the insulated gas collection chamber 1 with the top gas phase space of the storage tank. It is used to introduce the gas in the storage tank into the insulated gas collection chamber 1 for pre-cooling and return it to the storage tank by means of natural thermal convection before the breather valve of the storage tank is opened.

[0036] This invention is not limited to passive treatment after exhaust gas discharge, but adds a source-suppression pre-cooling circuit 6. In the initial stage of tank heating after sunrise (when the tank pressure is rising but has not yet reached the exhaust pressure of the breather valve), the device utilizes the inherent density difference between hot and cold air to create a "thermal siphon" effect. The heated oil and gas at the top of the tank, under buoyancy, automatically enters the device's insulated gas collection chamber 1 through the rising gas pipe 61 of the pre-cooling circuit. Inside the gas collection chamber, the oil and gas are cooled by the radiative cooling condensation module at the top, resulting in a decrease in temperature, volume contraction, and increased density. It then automatically settles back into the tank through the downcomer 62. This zero-energy natural convection cycle creates a "local cold zone" inside the tank, effectively absorbing some of the heat input from solar radiation, thus significantly slowing down the expansion rate of the gas inside the tank and drastically reducing the frequency and volume of exhaust reaching the exhaust threshold at the source. When the daytime high temperature causes the tank pressure to eventually exceed the breather valve's set value, the exhaust recovery mode is activated. The discharged high-concentration oil and gas enters the insulated gas collection chamber 1.

[0037] The multi-stage cold trap in this invention is manifested in both spatial and temporal dimensions: in terms of time, it is divided into a first-stage pre-condensation (before the breather valve is opened) and a second-stage centralized condensation (after the breather valve is opened); in terms of space, it utilizes the same radiative cooling and condensation module to achieve multi-gradient temperature interception.

[0038] This invention requires no electrical drive. The radiative cooling condensation module 2 radiates heat into space through its spectrally selective radiative cooling layer 22 on its outer surface, utilizing the principle of passive radiative cooling to achieve sub-ambient temperature cooling. The source suppression pre-cooling circuit 6 utilizes the thermal density difference formed during the initial heating of the storage tank, spontaneously forming a thermosiphon-type natural convection circulation through the rising gas pipe 61 and the descending liquid-gas mixing pipe 62. The synergistic effect of these components makes this invention particularly suitable for scenarios without a stable power supply, such as remote well sites and offshore platforms.

[0039] Before the breather valve opens, high-temperature gas from the top of the storage tank is introduced into the insulated gas collection chamber 1 via the source suppression pre-cooling circuit 6. After pre-cooling by the radiant cooling condensing module 2, the gas flows back into the storage tank, forming a "local cold zone" inside the tank. This slows down the pressure rise and reduces the breathing frequency from the source. When the pressure reaches the breather valve's set value, the differential pressure balancing valve 63 closes the pre-cooling circuit and switches to the centralized condensation recovery mode. The same radiant cooling condensing module 2 efficiently condenses the discharged oil and gas. The two modes are seamlessly switched via the differential pressure balancing valve 63.

[0040] This invention integrates macroscopic turbulence units and microscopic liquid guiding channels on the condenser fins 23. The macroscopic turbulence units create turbulence in the flowing oil and gas, prolonging the residence time and disrupting the thermal boundary layer; the microscopic liquid guiding channels, combined with a superoleophobic micro / nano composite coating, allow the condensate to rapidly self-displace in bead-like form, avoiding liquid film thermal resistance. The synergistic effect of these structures achieves highly efficient condensation of lightweight VOCs components under zero-energy consumption conditions.

[0041] This invention integrates the heat-insulating gas collection chamber 1, the radiative cooling condensing module 2, the reflux liquid guiding mechanism 3, and the source suppression pre-cooling circuit 6 into one unit. The whole unit has a cap-like structure and can be directly flange-connected to the top of the breather valve of the existing storage tank without laying pipelines and cables, without changing the original storage tank structure, thus reducing the difficulty and cost of modification.

[0042] The radiation cooling and condensation module 2 includes a high thermal conductivity substrate 21, which has a side facing the external sky and a side facing the interior of the adiabatic gas collection cavity 1. A spectrally selective radiation cooling layer 22 is provided on the side of the high thermal conductivity substrate 21 facing the sky, and this layer 22 is used to radiate heat into space. Several condensation fins 23 extend from the side of the high thermal conductivity substrate 21 facing the interior of the adiabatic gas collection cavity. These condensation fins 23 are used for heat exchange with the oil and gas inside the cavity. A condensation enhancement component is provided on the condensation fins 23. The condensation enhancement component consists of a macroscopic turbulence unit and a microscopic liquid guiding channel. The macroscopic turbulence unit prolongs the residence time of oil and gas on the cold surface and induces gas turbulence to disrupt the gas thermal boundary layer. The microscopic liquid guiding channel accelerates the self-displacement of condensate droplets through capillary action and gravity, thereby renewing the condensation surface.

[0043] The high thermal conductivity substrate 21 simultaneously supports the spectrally selective radiation cooling layer 22 and the condensation fins 23, forming a low thermal resistance heat transfer path from the cold source (radiation cooling layer) to the heat exchange interface (condensation fins), ensuring that the cooling capacity generated by radiation cooling is efficiently transferred to the oil and gas condensation area. The macroscopic turbulence unit and microscopic liquid guiding channel integrated on the condensation fins 23 respectively enhance convective heat transfer and droplet detachment at the heat exchange interface. The two are functionally coupled through the high thermal conductivity substrate 21, enabling the device to achieve a high overall condensation efficiency without external power.

[0044] The condenser fins 23 are simultaneously equipped with the macroscopic turbulence unit and the microscopic liquid guiding channel. The macroscopic turbulence unit significantly improves convective heat transfer efficiency by extending the residence time of oil and gas and inducing turbulence to disrupt the gas thermal boundary layer. The microscopic liquid guiding channel accelerates the self-displacement of condensed droplets through capillary action and gravity, thereby achieving high-frequency renewal of the condensation surface. The synergistic effect of both effectively avoids the formation of liquid film thermal resistance, enabling efficient condensation of light oil and gas components even under limited natural temperature differences.

[0045] The radiative cooling condensing module 2, covering the top of the insulated gas collection cavity, is the core heat exchange component. Structurally, it uses a high thermal conductivity metal substrate (such as aluminum alloy or copper). Its outer surface (facing the sky) is coated with a spectrally selective radiative cooling coating. This coating is designed to have extremely high reflectivity (>95%) in the 0.3-2.5μm wavelength band to reject solar heat load; and extremely high emissivity (>90%) in the 8-13μm wavelength band to radiate heat into space through atmospheric windows. This allows the module surface temperature to remain 5-10°C lower than the ambient temperature even under direct midday sunlight, and even lower at night. To address the challenges of limited temperature differences and insufficient condensation of lightweight components (such as pentane, hexane, and other low dew point components) under natural cold sources, this invention innovatively designs a synergistic structure on the fins of the radiative cooling condensing module 2, combining macroscopic turbulence and microscopic liquid guiding. Interlaced louvered slits or turbulence baffles are added to the condensing fin area, forcing the straight upward and downward oil and gas flow lines to bend, forming vortices and turbulence. This not only significantly increases the residence time of oil and gas in the cold zone, but also breaks down the laminar thermal boundary layer attached to the fin surface, greatly improving the convective heat transfer coefficient. The surface of the condenser fin substrate is processed with downward-extending micron-scale arrayed grooves, and grafted with modified materials to generate a superoleophobic micro / nano composite coating (such as fluorosilane-modified silica particles). Once the oil and gas condense, due to the extremely low surface energy (contact angle > 150°, roll-off angle < 10°), the condensate cannot form a film, but instead forms droplets. Under the capillary guidance of the micron-grooves and the combined effect of gravity, the droplets rapidly slide off and self-repel, exposing the exposed condensation surface and ensuring the continuous and efficient operation of the condensation core.

[0046] The macroscopic turbulence unit includes staggered louver-type slits or stamped flow guide baffles on the surface of the condensing fins 23. The stamped flow guide baffles on adjacent fins are staggered to create an S-shaped or spiral turbulent flow field for the flowing oil-gas mixture. The staggered arrangement of the louver-type slits or stamped flow guide baffles on adjacent fins forces the flowing oil-gas mixture to continuously change its flow direction, forming an S-shaped or spiral turbulent flow field. This effectively disrupts the laminar thermal boundary layer of gas adhering to the fin surface, significantly enhancing the convective heat transfer coefficient and improving condensation efficiency.

[0047] The microscopic liquid guiding channels include an array of micrometer-scale grooves extending along the direction of gravity on the surface of the fin substrate. Both the groove array and the fin surface are covered with a superoleophobic micro / nano composite coating. This superoleophobic micro / nano composite coating provides a contact angle greater than 150° and a roll-off angle less than 10° for alkane liquids with a surface tension greater than 20 mN / m. The superoleophobic coating causes alkane condensates to condense into spherical droplets with a contact angle greater than 150° and a roll-off angle less than 10°, effectively avoiding the thermal resistance generated by liquid film formation. Simultaneously, the micrometer-scale groove array extending along the direction of gravity guides the condensate droplets rapidly away from the fin surface through capillary action and gravity, achieving high-frequency renewal of the condensation surface and ensuring a continuous and efficient condensation process.

[0048] The source suppression pre-cooling circuit 6 includes an ascending gas pipe 61 and a descending liquid-gas mixing pipe 62. One end of the ascending gas pipe 61 is connected to the highest point of the top of the storage tank and communicates with the storage tank, while the other end is connected to the upper part of the insulated gas collection chamber 1. One end of the descending liquid-gas mixing pipe 62 is connected to the bottom liquid collection area of ​​the insulated gas collection chamber 1, while the other end extends into the interior of the storage tank. Under thermal convection conditions, the gas at the top of the storage tank enters the insulated gas collection chamber 1 through the ascending gas pipe 61, and after being cooled, carries the condensate back to the storage tank through the descending liquid-gas mixing pipe 62, forming a thermosiphon natural convection circulation.

[0049] With the above-mentioned structural design, without any external power, the gas at the top of the tank expands when heated, decreases in density and rises naturally, and increases in density after cooling and settles naturally. This spontaneously forms a thermosiphon-type natural convection circulation, continuously transporting the cooling energy generated by radiative cooling into the tank. Before the breather valve is opened, the pressure rise inside the tank is actively suppressed, reducing the amount of breath emissions at the source.

[0050] The rising gas pipe 61 of the source suppression precooling circuit 6 is equipped with a differential pressure balancing valve 63. When the pressure inside the storage tank is lower than the opening pressure of the breather valve and there is thermal convection, the differential pressure balancing valve 63 is in the normally open state, allowing the gas at the top of the storage tank to enter the insulated gas collection chamber 1 through the rising gas pipe 61 for precooling and reflux. When the pressure inside the storage tank reaches the setting pressure of the breather valve, the differential pressure balancing valve 63 is closed, and the waste gas from the storage tank enters the insulated gas collection chamber 1 through the air inlet 11 for centralized condensation.

[0051] The differential pressure balancing valve 63 is installed on the rising gas pipe 61. Through automatic switching of its opening and closing states, it achieves decoupling and seamless connection between the source suppression mode and the centralized condensation and recovery mode: when the pressure inside the storage tank is lower than the set pressure for opening the breather valve, the differential pressure balancing valve 63 is normally open, allowing gas from the top of the storage tank to preferentially enter the insulated gas collection chamber 1 through the rising gas pipe 61 for pre-cooling and reflux, reducing emissions at the source; when the pressure inside the storage tank reaches the set pressure for the breather valve, the differential pressure balancing valve 63 automatically closes, forcing the exhaust gas from the storage tank to enter the insulated gas collection chamber 1 through the air inlet 11 for centralized condensation, preventing high-concentration oil and gas from directly escaping through the pre-cooling circuit without condensation, ensuring the recovery efficiency of end-of-pipe treatment. This structure achieves automatic switching between the two operating modes in a passive manner, requiring no additional control components or energy consumption.

[0052] It also includes a thermal diode assembly 5, which is embedded at the connection between the radiative cooling condensation module 2 and the adiabatic gas collection cavity 1. This assembly allows heat to be conducted unidirectionally from the adiabatic gas collection cavity 1 to the radiative cooling condensation module 2. The thermal diode assembly 5, embedded at the connection between the radiative cooling condensation module 2 and the adiabatic gas collection cavity 1, allows heat to be conducted unidirectionally from the gas collection cavity to the radiative cooling layer, and cuts off the reverse flow of external heat in the event of extreme high temperatures or coating failure.

[0053] The radiant cooling condensing module 2 is generally arranged in the shape of an inverted frustum or funnel. The condensing fins 23 are radially distributed along the conical surface, and the bottom of the fins is inclined towards the center of the adiabatic gas collection chamber 1. The reflux guiding mechanism 3 includes a liquid collection funnel 31 and a U-shaped liquid seal pipe 32. The liquid collection funnel 31 is located at the drain port 12, and the U-shaped liquid seal pipe 32 is connected to the bottom of the liquid collection funnel 31. A safety bypass valve 4 is also provided on the side wall of the adiabatic gas collection chamber 1. The opening pressure setting value of the safety bypass valve 4 is higher than the opening pressure of the tank breather valve.

[0054] The radiant cooling condensing module 2 is generally arranged in the shape of an inverted frustum or funnel. The condensing fins 23 are radially distributed along the conical surface and the bottom end is inclined towards the center of the adiabatic gas collection chamber 1. This structure allows the condensed liquid to automatically converge towards the center under the action of gravity, forming an efficient liquid collection path with the liquid collection funnel 31 located at the drain port 12. The U-shaped liquid seal pipe 32 is connected to the bottom of the liquid collection funnel 31. It uses the liquid seal principle to prevent gas from escaping directly from the drain port 12, ensuring that the condensate is unidirectionally guided back to the storage tank while avoiding short-circuit leakage of oil and gas. The safety bypass valve 4 is located on the side wall of the adiabatic gas collection chamber 1. Its opening pressure setting value is higher than the opening pressure of the storage tank breather valve. When the flow channel of the condensing module is blocked, causing the back pressure to rise abnormally, it directly releases pressure to the atmosphere, forming a safety redundancy protection independent of the condensing channel, avoiding overpressure deformation of the storage tank, and improving the operational reliability of the system.

[0055] The spectrally selective radiation cooling layer 22 has a solar reflectivity greater than 0.95 in the 0.3-2.5μm wavelength band and a thermal emissivity greater than 0.90 in the 8-13μm wavelength band. This effectively reflects most of the solar radiation heat, preventing the device from overheating due to sunlight. Simultaneously, its thermal emissivity of greater than 0.90 in the 8-13μm atmospheric window band allows it to efficiently transmit heat as infrared radiation through the atmospheric window into space. The synergistic effect of these two elements enables the radiation cooling condensation module 2 to achieve passive cooling below ambient temperature even under direct sunlight during the day, providing a continuous and stable natural cold source for oil and gas condensation and ensuring effective operation of the device under all-weather conditions.

[0056] This invention also relates to a recovery method for a storage tank oil and gas suppression and recovery device based on radiative cooling and a multi-stage cold trap, comprising the following steps:

[0057] Source suppression step: When the pressure inside the storage tank is lower than the set pressure for opening the breather valve and thermal convection conditions exist, the differential pressure balance valve 63 opens. Under the action of natural thermal convection, the gas in the gas phase space at the top of the storage tank enters the upper part of the insulated gas collection chamber 1 through the rising gas pipe 61 and exchanges heat with the radiant cooling condensing module 2. After the gas is cooled, its density increases, and it carries some condensate back to the inside of the storage tank through the descending liquid-gas mixing pipe 62, forming a thermosiphon-type natural convection circulation to suppress the pressure rise inside the storage tank. Centralized condensation and recovery step: When the pressure inside the storage tank reaches the set pressure for opening the breather valve, the differential pressure balance valve 63 closes and the storage tank breather valve opens. The oil-gas mixture discharged from the storage tank enters the insulated gas collection chamber 1 through the air inlet 11. The oil-gas mixture is cooled on the surface of the condensing fins 23 of the radiant cooling condensing module 2, where the condensable components are condensed into liquid. The condensate is guided back to the inside of the storage tank in one direction through the return liquid guiding mechanism 3. In the centralized condensation and recovery step, when the oil-gas mixture flows through the condensation fins 23, it is subjected to macroscopic turbulence units to form turbulence, which disrupts the thermal boundary layer. The condensed droplets are self-driven away from the fin surface under the synergistic effect of the microscopic liquid guiding channels and the superoleophobic surface, thereby renewing the condensation surface.

[0058] By controlling the opening and closing state of the differential pressure balancing valve 63, the source suppression step and the centralized condensation recovery step are automatically switched according to the pressure change in the storage tank without the need for external control signals or power: when the pressure is lower than the set pressure for opening the breather valve, source suppression is performed; when the pressure reaches the set pressure, it automatically switches to centralized condensation recovery, thus achieving decoupling and seamless connection between the two working modes.

[0059] The source suppression step utilizes thermosiphon-type natural convection circulation to actively introduce high-temperature gas from the top of the storage tank into the insulated gas collection chamber 1 for pre-cooling and recirculation before the breather valve opens, thus delaying pressure rise and reducing breathing frequency at the source. The centralized condensation and recovery step efficiently condenses and recovers the discharged oil and gas after the breather valve opens. The two steps work synergistically to achieve dual intervention of prevention and control, resulting in a comprehensive emission reduction effect superior to single end-of-pipe treatment methods.

[0060] In the centralized condensation and recovery step, when the oil and gas flow through the condensation fins 23, the macroscopic turbulence unit is used to form turbulence to destroy the gas thermal boundary layer, and the synergistic effect of the microscopic liquid guiding channel and the superoleophobic surface is used to drive the condensate droplets away from the fin surface, thereby achieving high-frequency renewal of the condensation surface and ensuring efficient condensation of light oil and gas components under limited natural temperature difference.

[0061] This embodiment proposes applying the device to a 500m³ crude oil / light hydrocarbon temporary storage tank at a remote well site in an oilfield. This storage tank lacks a stable power supply, and during the summer, due to intense sunlight exposure, the light hydrocarbons inside the tank undergo severe volatilization, frequently causing the breather valve to open and resulting in significant fugitive emissions. In this embodiment, the device is directly flange-connected to the breather valve flange interface on the top of the tank. The main body of the device includes a cylindrical insulated gas collection chamber 1 and an inverted conical radiant cooling and condensation module 2 at the top.

[0062] The outer wall of the insulated gas collection chamber 1 adopts a double-layer stainless steel internal vacuum structure with built-in anti-radiation shielding foil. The effective radiation area of ​​the radiant cooling condensation module 2 is 1.5m². 2 The outermost layer 22 is coated with a porous composite coating of nano-titanium dioxide / polyvinylidene fluoride-hexafluoropropylene copolymer (TiO2 / P(VdF-HFP)). Due to its rich micro-nano channel structure, this coating exhibits a reflectivity of up to 96.5% for sunlight (wavelength 0.3-2.5μm), while the vibrational frequency of its polymer bonds perfectly matches the 8-13μm atmospheric window, resulting in a thermal emissivity of 93%. In the fabrication of the condensation fins 23, a condensation enhancement treatment is implemented: a microgroove array with a width of 50μm and a depth of 30μm is machined on the surface of the aluminum alloy fins along the direction of gravity using laser engraving technology. Subsequently, louver-type baffles (within a 30° angle) are staggered and stamped onto the fin surface. Finally, a low surface energy molecular layer of perfluorodecyltrichlorosilane (FDTS) is grafted onto the entire fin surface using chemical vapor deposition (CVD). Contact angle tests showed that the surface had a contact angle of up to 158° with n-hexane and a roll-off angle as low as 3°.

[0063] Preventative source suppression process (early morning to mid-morning): From 8:00 AM to 11:00 AM, solar radiation gradually intensifies, the outer wall of the storage tank absorbs heat, and the temperature of the gas phase space inside the tank begins to rise from 20°C to 30°C. At this time, the pressure inside the tank rises slightly, but has not yet reached the positive pressure exhaust opening value set by the breather valve (e.g., 1.5 kPa). At this time, the source suppression pre-cooling circuit 6 comes into play. As the top radiative cooling module 2 continuously radiates heat to space, the temperature of its internal fins is maintained at around 15°C. The hotter oil and gas (lower density) that expands due to heat at the top of the tank floats into the insulated gas collection chamber 1 through the rising gas pipe 61, and is cooled after contacting the condensing fins, shrinking in volume and increasing in density. Subsequently, this cooler heavy gas mixed with some initial condensed droplets settles back into the storage tank through the descending liquid-gas mixing pipe 62. This process forms a stable "thermal siphon" natural circulation, continuously "transporting" the cold energy from space into the tank, offsetting the thermal expansion effect brought by sunlight. Monitoring data shows that the time it takes for a storage tank equipped with a pre-cooling circuit to first break through the breather valve and exhaust pressure is delayed by nearly 3 hours compared to a conventional storage tank, and the daily exhaust frequency decreases.

[0064] Extremely High Temperature Exhaust Gas Recovery Process (Noon to Afternoon): At noon, the ambient temperature reaches 38℃, and the pressure inside the tank suddenly rises, exceeding the set value of the breather valve. A large amount of high-concentration VOCs mixed gas rushes into the insulated gas collection chamber 1. At this time, the "end-of-pipe treatment" mode is entered. When the oil and gas flow passes through the condenser fins 23, the flow direction is changed multiple times by the louvered macroscopic turbulence baffles. The forced vortex and turbulence cause the originally laminar gas to mix violently. The high-temperature gas flow continuously impacts the condenser surface, which is maintained at about 28℃ by radiative cooling (10℃ lower than the ambient temperature), prolonging the residence time of light components. Components such as pentane and hexane in the oil and gas reach the dew point on the fin surface and condense instantly. Due to the superoleophobic state of the surface and the presence of micron-sized liquid guide grooves, the condensed micro-droplets cannot gather into a liquid film that hinders heat transfer. Instead, under the pull of microgravity and capillary force, they slide down the grooves at high speed like "marbles". This "droplet condensation-self-destruction" mechanism improves the convective heat transfer coefficient. The collected condensate falls into the collection funnel 31 and is smoothly guided back to the storage tank through the U-shaped liquid seal pipe 32. The liquid column height inside the U-shaped pipe is designed to be greater than the exhaust pressure head of the breather valve, thus ensuring a tight seal against gas short-circuiting and leakage while the liquid is being returned.

[0065] If a severe sandstorm covers the coating, causing radiative cooling to fail and the environment to be extremely hot (e.g., 45°C), the working fluid inside the thermal diode assembly 5 will accumulate at the bottom without undergoing a phase change, cutting off the heat conduction path from top to bottom. If the back pressure in the gas collecting chamber is too high at this time, the safety bypass valve 4 will open at 2.0 kPa to release pressure, ensuring that the storage tank does not experience overpressure deformation and guaranteeing the absolute safety of the system.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A storage tank oil and gas suppression and recovery device based on radiative cooling and multi-stage cold traps, characterized in that, include: The insulated gas collection chamber (1) has an air inlet (11) and a drain outlet (12) at its bottom. The air inlet (11) is used to connect with the breather valve of the storage tank. A radiation cooling condensation module (2) is placed over the top opening of the adiabatic gas collection chamber (1) and is used to condense the oil-gas mixture entering the adiabatic gas collection chamber (1) by means of passive radiation cooling. The reflux guiding mechanism (3) is connected to the drain port (12) and is used to guide the condensed liquid back into the storage tank in one direction; as well as The source suppression pre-cooling circuit (6) connects the insulated gas collection chamber (1) with the top gas phase space of the storage tank. It is used to introduce the gas in the storage tank into the insulated gas collection chamber (1) for pre-cooling and return to the storage tank by means of natural heat convection before the breathing valve of the storage tank is opened.

2. The storage tank oil and gas suppression and recovery device based on radiative cooling and multi-stage cold traps according to claim 1, characterized in that, The radiation cooling condensation module (2) includes a high thermal conductivity substrate (21), which has a side facing the external sky and a side facing the interior of the adiabatic gas collection cavity (1). The side of the high thermal conductivity substrate (21) facing the sky is provided with a spectrally selective radiation cooling layer (22), which is used to radiate heat into space. The side of the high thermal conductivity substrate (21) facing the interior of the adiabatic gas collection cavity is provided with a number of condensation fins (23), which are used to exchange heat with the oil and gas in the cavity. The condensation fins (23) are provided with condensation enhancement components. The condensation enhancement components are a macroscopic turbulence unit and a microscopic liquid guiding channel. The macroscopic turbulence unit is used to prolong the residence time of oil and gas on the cold surface and induce gas to form turbulence, so as to destroy the gas thermal boundary layer. The microscopic liquid guiding channel is used to accelerate the self-displacement of condensed droplets through capillary action and gravity, so as to realize the renewal of the condensation surface.

3. The storage tank oil and gas suppression and recovery device based on radiative refrigeration and multi-stage cold traps according to claim 2, characterized in that, The macroscopic turbulence unit includes louvered slits or stamped flow guides staggered on the surface of the condenser fins (23); the stamped flow guides on adjacent fins are staggered to form an S-shaped or spiral turbulent flow field for the oil-gas mixture flowing through.

4. The storage tank oil and gas suppression and recovery device based on radiative refrigeration and multi-stage cold traps according to claim 2, characterized in that, The micro-fluid guiding channel includes a micron-scale trench array extending along the direction of gravity on the surface of the fin substrate; both the trench array and the fin surface are covered with a superoleophobic micro-nano composite coating. The superoleophobic micro / nano composite coating has a contact angle greater than 150° and a roll-off angle less than 10° for alkane liquids with a surface tension greater than 20 mN / m.

5. The storage tank oil and gas suppression and recovery device based on radiative cooling and multi-stage cold traps according to claim 1, characterized in that, The source suppression precooling circuit (6) includes an ascending gas pipe (61) and a descending liquid-gas mixing pipe (62); one end of the ascending gas pipe (61) is connected to the highest point of the top of the storage tank and communicates with the storage tank, and the other end is connected to the upper part of the insulated gas collection chamber (1); one end of the descending liquid-gas mixing pipe (62) is connected to the bottom liquid collection area of ​​the insulated gas collection chamber (1), and the other end extends into the inside of the storage tank; under thermal convection conditions, the gas at the top of the storage tank enters the insulated gas collection chamber (1) through the ascending gas pipe (61), and after being cooled, carries the condensate back to the storage tank through the descending liquid-gas mixing pipe (62), forming a thermosiphon natural convection circulation.

6. The storage tank oil and gas suppression and recovery device based on radiative cooling and multi-stage cold traps according to claim 5, characterized in that, The source suppression precooling circuit (6) is equipped with a differential pressure balancing valve (63) on the rising gas pipe (61). When the pressure inside the storage tank is lower than the opening pressure of the breather valve and there is thermal convection, the differential pressure balancing valve (63) is normally open, allowing the gas at the top of the storage tank to enter the insulated gas collection chamber (1) through the rising gas pipe (61) for precooling and reflux. When the pressure inside the storage tank reaches the setting pressure of the breather valve, the differential pressure balancing valve (63) is closed, and the waste gas from the storage tank enters the insulated gas collection chamber (1) through the air inlet (11) for centralized condensation.

7. The storage tank oil and gas suppression and recovery device based on radiative cooling and multi-stage cold traps according to claim 1, characterized in that, It also includes a thermal diode assembly (5), which is embedded at the connection between the radiative cooling condensing module (2) and the adiabatic gas collection chamber (1) to allow heat to be conducted unidirectionally from the adiabatic gas collection chamber (1) to the radiative cooling condensing module (2).

8. The storage tank oil and gas suppression and recovery device based on radiative cooling and multi-stage cold traps according to claim 1, characterized in that, The radiant cooling condensing module (2) is generally arranged in the shape of an inverted frustum or a funnel. The condensing fins (23) are radially distributed along the conical surface, and the bottom of the fins is inclined towards the center of the adiabatic gas collection chamber (1). The reflux liquid guiding mechanism (3) includes a liquid collection funnel (31) and a U-shaped liquid seal pipe (32). The liquid collection funnel (31) is located at the drain port (12), and the U-shaped liquid seal pipe (32) is connected to the bottom of the liquid collection funnel (31). A safety bypass valve (4) is also provided on the side wall of the adiabatic gas collection chamber (1). The opening pressure setting value of the safety bypass valve (4) is higher than the opening pressure of the tank breather valve.

9. The storage tank oil and gas suppression and recovery device based on radiative refrigeration and multi-stage cold traps according to claim 1, characterized in that, The spectrally selective radiation cooling layer (22) has a solar reflectivity greater than 0.95 in the 0.3-2.5 μm band and a thermal emissivity greater than 0.90 in the 8-13 μm band.

10. A recovery method for a storage tank oil and gas suppression and recovery device based on radiative refrigeration and a multi-stage cold trap according to any one of claims 1 to 9, characterized in that, Includes the following steps: Source suppression step: When the pressure inside the storage tank is lower than the set pressure for opening the breather valve and there is thermal convection, the differential pressure balance valve (63) opens. Under the action of natural thermal convection, the gas in the gas phase space at the top of the storage tank enters the upper part of the insulated gas collection chamber (1) through the rising gas pipe (61) and exchanges heat with the radiant cooling condensing module (2). After the gas is cooled, the density increases and carries some condensate back to the inside of the storage tank through the descending liquid-gas mixing pipe (62), forming a thermosiphon natural convection circulation to suppress the pressure rise inside the storage tank. Centralized condensation and recovery step: When the pressure inside the storage tank reaches the set pressure for opening the breather valve, the differential pressure balance valve (63) closes and the storage tank breather valve opens. The oil-gas mixture discharged from the storage tank enters the insulated gas collection chamber (1) through the air inlet (11). The oil-gas mixture is cooled on the surface of the condensing fins (23) of the radiant cooling condensing module (2), where the condensable components are condensed into liquid. The condensate is guided back to the inside of the storage tank in one direction through the return liquid guiding mechanism (3). In the centralized condensation and recovery step, when the oil-gas mixture flows through the condensation fins (23), it is subjected to macroscopic turbulence units to form turbulence, thereby destroying the thermal boundary layer. The condensed droplets are self-driven away from the fin surface under the synergistic effect of the microscopic liquid guiding channels and the superoleophobic surface, thus achieving the renewal of the condensation surface.

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