Ultralow-temperature condensation and ultralow-emission oil gas recovery system and method

Abstract

The invention belongs to the technical field of oil gas recovery, and discloses an ultralow-temperature condensation and ultralow-emission oil gas recovery system and method.A component self-adaptive gradient matching mixed working medium is adopted to be matched with a single-stage inverter compressor, oil gas component online detection and an AI algorithm are combined, the working medium ratio can be dynamically adjusted so as to accurately meet the refrigeration requirements of oil gas with different components, and the oil gas recovery efficiency is improved. A complicated cascade refrigeration structure is not needed, so that the operation stability is improved while the system is simplified; due to the design of the integrated composite heat exchanger, the heat exchange structure is optimized, the cold energy loss is reduced, the heat exchange efficiency is improved, a stable ultralow-temperature cold source is provided for oil-gas deep condensation separation, and oil-gas deep separation is guaranteed from the refrigeration end; the pre-separation module integrates multiple pretreatment functions, strictly controls the cleanliness of oil gas through a secondary pretreatment mechanism, removes impurities in the oil gas, prevents the impurities from blocking, abrading and other influences on the system in an ultralow-temperature environment, and guarantees continuous operation of the system.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas recovery technology, specifically a cryogenic condensation and ultra-low emission oil and gas recovery system and method. Background Technology

[0002] In the refining, storage, transportation, loading, unloading, and sales of petroleum, a large amount of volatile organic compounds (VOCs) are generated. These VOCs not only cause a serious waste of petroleum resources, but also, once released into the atmosphere, are important precursors to air pollutants such as ozone and PM2.5, seriously endangering the ecological environment and human health. Existing oil and gas recovery technologies mainly include condensation, absorption, adsorption, membrane separation, and combined processes. Among these, condensation has become the mainstream technology due to its ability to directly and continuously recover hydrocarbon components, without adsorbent / absorbent consumption or secondary pollution, and is particularly suitable for gas mixture condensation separation and distillation separation scenarios. However, existing condensation-based oil and gas recovery systems still have the following technical problems: Existing technologies mostly employ two- or three-stage cascade refrigeration, resulting in limited cooling depth. Currently, the NMHC concentration limit for ultra-low emissions in the oil and gas recovery industry is ≤30mg / m³, which existing condensation technologies struggle to meet. Furthermore, three-stage cascade refrigeration systems suffer from complex structures, difficult inter-stage matching, and low operational reliability. They also exhibit low cold energy utilization efficiency, with some systems using direct liquid nitrogen cooling, resulting in significant waste of high-grade, low-temperature cold energy and failing to meet energy conservation and emission reduction requirements. Incomplete oil and gas pretreatment means that minute oil mists, moisture, and impurities in the oil and gas are prone to freezing and clogging pipelines in ultra-low temperature environments, affecting continuous system operation. After condensation, the oil and gas are not completely separated from the air, and a small amount of light hydrocarbon components are emitted with the exhaust gas, making it impossible to achieve true ultra-low emissions. Existing separation systems are mostly single condensation or single distillation modes, which do not achieve precise matching and deep synergy of the separation process, and do not achieve graded recovery for different hydrocarbon components. The separation efficiency and resource recovery rate need to be improved. Summary of the Invention

[0003] The purpose of this invention is to provide an ultra-low temperature condensation ultra-low emission oil and gas recovery system and method to solve one or more problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: an ultra-low temperature condensation ultra-low emission oil and gas recovery system, comprising the following specific modules: Preferably, the cryogenic refrigeration module employs a component adaptive gradient ratio mixed working fluid, which is composed of neon, nitrogen, low-carbon alkanes, and hydrofluorocarbons. Combined with a single-stage variable frequency compressor and a segmented regenerator, it achieves cryogenic refrigeration at -170℃ to -120℃. An online oil and gas component detection unit is installed to collect the proportions of light and heavy hydrocarbons in the pre-separated oil and gas in real time. An AI adaptive algorithm dynamically adjusts the mass concentration of each component in the mixed working fluid to match the refrigeration temperature with the oil and gas composition. When the proportion of light hydrocarbons is high, the proportion of low-boiling-point working fluid is increased, lowering the refrigeration temperature to -150℃ to -170℃; when the proportion of heavy hydrocarbons is high, the proportion of high-boiling-point working fluid is increased, maintaining the refrigeration temperature at -120℃ to -140℃. The evaporator, the top condenser of the distillation column, and the bottom reboiler are integrated into a single composite heat exchanger. It adopts a high-efficiency heat exchange structure, with irregularly shaped heat exchange tubes made of corrosion-resistant alloy material and fins with a serrated structure to increase the heat exchange area. It provides an ultra-low temperature cold source for the system to meet the temperature requirements for oil-gas condensation and separation.

[0005] Preferably, the pre-separation module utilizes the cold energy generated by the ultra-low temperature refrigeration module in a graded and stepped manner, extracting a portion of the medium- and low-temperature cold energy to achieve gradient low-temperature dehydration. Simultaneously, it receives upstream oil and gas feedstock, integrating cyclone separation, electrostatic dust removal, and gradient low-temperature dehydration into a single process. This removes tiny oil mist, solid dust, and moisture with a particle size ≤10μm from the oil and gas. The electrostatic dust removal unit employs a low-temperature adaptable honeycomb electrode structure, with an anti-condensation coating sprayed onto the electrode surface. This anti-condensation coating is made of polytetrafluoroethylene (PTFE). An adaptive electrode cleaning control is also implemented, dynamically adjusting the electric field strength based on the amount of dust accumulation. The low-temperature dehydration unit uses a gradient pre-cooling and adsorption-assisted dehydration composite structure. It first cools to 5℃ to remove most of the moisture, then cools to -20℃ to remove trace amounts of free water, and finally achieves a residual moisture content of ≤10ppm through modified molecular sieve adsorption. The pre-separation module is also equipped with a pre-treated oil and gas purity detection unit, which is used to provide real-time feedback on impurity content. If impurities are detected to exceed the standard, a secondary cycle pre-treatment is automatically triggered to provide clean oil and gas feedstock for the distillation and condensation module.

[0006] Preferably, the distillation and condensation module receives the clean oil and gas delivered by the pre-separation module and utilizes the ultra-low temperature cold source provided by the ultra-low temperature refrigeration module to construct an integrated separation structure for ultra-low temperature condensation, staged distillation and stripping purification. It adopts composite packing adapted to the ultra-low temperature environment, an integrated condenser-evaporator is set at the top of the column, a low temperature reboiler is set at the bottom of the column, and 2-3 intermediate liquid collection sections are added in the middle of the column to collect hydrocarbon components with different boiling points, so as to realize the staged recovery of hydrocarbons with different boiling points. After pre-separation, the oil and gas enter the distillation and condensation module. Under ultra-low temperature conditions, most of the heavy hydrocarbon components are liquefied and recovered through condensation. The remaining mixture of light hydrocarbons and air enters the rectification section. Through staged distillation, the light hydrocarbon components are separated in stages. High-boiling-point light hydrocarbons are condensed and recovered in the lower part of the rectification section, while low-boiling-point light hydrocarbons enter the upper part of the rectification section. After further purification by the stripping unit, they are condensed and recovered. Clean air is discharged through the top of the tower. Online detection units for oil and gas components are installed in each section of the distillation column to monitor the hydrocarbon component content in real time. The distillation temperature and reflux ratio are dynamically adjusted through AI algorithms to ensure the separation of light hydrocarbons from air. The NMHC concentration in the tail gas is less than 20 mg / m³. The cold energy and waste heat generated during operation provide a source for the waste heat recovery module.

[0007] Preferably, the self-defrosting module adopts a dual-evaporator alternating operation and residual cooling and residual heat synergistic defrosting structure, and is equipped with two parallel ultra-low temperature evaporators. The evaporators use high-efficiency heat exchange materials and are equipped with an online frost thickness detection unit to monitor the frost thickness in real time. When the frost thickness reaches a set threshold, the evaporator working state is automatically switched to realize adaptive switching between condensation operation and defrosting standby. During defrosting, the low-temperature cold energy from the waste heat recovery module is mixed with the system's waste heat to form a mild heat exchange medium of 0~5℃. The frost-covered evaporator is then defrosted without temperature difference through the heat exchange coil. Combined with the system's waste heat, this achieves defrosting without downtime and with low energy consumption.

[0008] Preferably, the waste cooling recovery module recovers and utilizes the waste cooling and waste heat generated during the operation of each module, including the ultra-low temperature refrigeration module, the distillation condensation module, and the self-defrosting module, to construct a full-process waste cooling and waste heat synergistic recovery system. The recovered waste cooling includes the low-temperature waste cooling of the clean air discharged from the top of the distillation column, the low-temperature waste cooling of the hydrocarbon condensation recovery, and the low-temperature waste cooling of the refrigeration module regenerator. The waste heat generated during the system operation is recovered simultaneously. The recovered waste cooling and waste heat are reused in stages through multi-stage high-efficiency heat exchangers. The low-temperature waste cooling of the clean air is used for oil and gas precooling, and the low-temperature waste cooling of the hydrocarbon condensation recovery is used for mixed working fluid precooling. The low-temperature waste cooling of the refrigeration module regenerator is exchanged with the system waste heat through temperature difference heat exchange. The energy grade of the low-temperature waste cooling is improved through waste heat, forming a heating medium suitable for the reboiler at the bottom of the distillation column, providing it with heat. The waste cooling recovery module is also equipped with a waste cooling storage unit to realize closed-loop reuse of waste cooling. The recovered cold energy provides a guarantee for the low-energy defrosting of the self-defrosting module.

[0009] Preferably, the metering feedback module adopts a multi-parameter linkage metering, real-time data feedback and AI dynamic calibration mode. Sensors are installed at the top exhaust port of the distillation column, the oil and gas inlet, the recovery liquid outlet and each intermediate liquid collection section of the distillation column to monitor the NMHC concentration, oil and gas flow rate, temperature, pressure, recovery liquid flow rate and hydrocarbon component content in the tail gas in real time. The metering coefficient is dynamically corrected by AI algorithm to realize the metering of recovery amount, emission amount and recovery rate of each component. The monitoring data is fed back to the intelligent control module in real time, providing data basis for the dynamic adjustment of refrigeration temperature, distillation parameters, mixed working fluid ratio, and defrosting sequence. At the same time, it provides a basis for environmental protection acceptance, resource accounting, and optimization of hydrocarbon graded recovery.

[0010] Preferably, the intelligent control module integrates the operating data of the ultra-low temperature refrigeration module, the pre-separation module, the distillation and condensation module, the self-defrosting module, the waste heat recovery module, and the metering feedback module, as well as the monitoring data of the metering feedback module. It collects the operating data of each module in real time through sensors, including refrigeration temperature, oil and gas flow rate, impurity content, frost layer thickness, emission concentration, and hydrocarbon component content in each section. It uses a gradient boosting decision tree machine learning algorithm to realize the dynamic coordinated control of each module, and constructs a three-dimensional coordinated control model with separation accuracy, energy consumption, and operational stability as the core to achieve multi-objective optimization. Based on changes in oil and gas intake flow rate and composition, the mixing ratio and refrigeration power of the working fluid are automatically adjusted; based on the frost layer thickness and distillation load, the evaporator operating status is automatically switched; based on the hydrocarbon component content of each section, the temperature gradient and reflux ratio of the distillation column are automatically adjusted; and based on the amount of waste cooling and waste heat recovered, the energy utilization path is dynamically allocated. The system is equipped with fault warning and self-repair functions, which can promptly detect problems such as pipe blockage, abnormal cooling, and decreased separation accuracy and issue audible and visual warnings. For minor faults, it can automatically adjust relevant parameters to achieve self-repair.

[0011] This invention also provides a method for recovering ultra-low emission oil and gas through cryogenic condensation, based on the above-mentioned system, comprising the following specific steps: S1: Performs ultra-low temperature refrigeration using a component-adaptive gradient ratio mixed working fluid, combined with a single-stage variable frequency compressor and segmented regenerative process. Through online detection of oil and gas components, AI algorithms dynamically adjust the working fluid ratio to achieve ultra-low temperature refrigeration from -170℃ to -120℃. The evaporator and distillation heat exchange equipment are integrated into a single composite heat exchanger. S2: Pre-processes the front-end oil and gas feedstock, utilizes the cold energy generated by the ultra-low temperature refrigeration module in a graded and stepped manner, extracts some medium and low temperature cold energy to achieve gradient low temperature dehydration, integrates cyclone separation, electrostatic dust removal and gradient low temperature dehydration functions, removes tiny oil mist, solid dust and trace moisture with a particle size ≤10μm from the oil and gas, ensures the cleanliness of the oil and gas through purity detection, and triggers secondary pre-processing when impurities exceed the standard; S3: Perform distillation and condensation separation, utilize ultra-low temperature cold source to construct an integrated separation process, adopt low temperature resistant and anti-frost composite packing, and achieve graded recovery of hydrocarbons with different boiling points through staged distillation and stripping purification, monitor hydrocarbon components in real time and adjust operating parameters to ensure that the NMHC concentration in the tail gas is below 20mg / m³. S4: During operation, dual evaporators work alternately and waste cooling and heat are used for defrosting. The frost thickness is monitored in real time and the working state is switched adaptively to achieve defrosting with low energy consumption and no downtime. At the same time, waste cooling and waste heat from each process are recovered to build a closed-loop reuse system and achieve graded energy utilization through multi-stage heat exchange. S5: Through multi-parameter linkage metering and AI dynamic calibration, it monitors operating data and feeds it back to the intelligent control module. It uses gradient boosting decision tree machine learning algorithm to achieve coordinated control of various processes. Combined with fault early warning and self-repair function, it improves oil and gas recovery rate and system operation reliability.

[0012] The beneficial effects of this invention are as follows: 1. This invention employs a component adaptive gradient ratio mixed working fluid paired with a single-stage variable frequency compressor. Combined with online detection of oil and gas components and AI algorithms, it can dynamically adjust the working fluid ratio to accurately match the refrigeration requirements of different oil and gas components. It eliminates the need for a complex cascade refrigeration structure, simplifying the system while improving operational stability. The integrated composite heat exchanger design optimizes the heat exchange structure, reduces energy loss, and improves heat exchange efficiency, providing a stable ultra-low temperature cold source for deep oil and gas condensation and separation, thus ensuring deep oil and gas separation from the refrigeration end.

[0013] 2. The pre-separation module of this invention integrates multiple pre-treatment functions. Through a secondary pre-treatment mechanism, it strictly controls the cleanliness of oil and gas, removes impurities from the oil and gas, and avoids the impact of impurities on the system such as blockage and wear in ultra-low temperature environments, ensuring continuous operation of the system. The distillation and condensation module constructs an integrated separation structure and uses low-temperature resistant and anti-frost composite packing. Through staged distillation and stripping purification, it achieves the staged recovery of hydrocarbons with different boiling points. Combined with AI algorithms to dynamically adjust operating parameters, it makes the separation of light hydrocarbons and air more thorough and improves the recovery and utilization rate of petroleum resources.

[0014] 3. The waste cooling recovery module of this invention comprehensively recovers and reuses the waste cooling and waste heat generated by each module during operation. The waste cooling storage unit realizes closed-loop reuse of cold energy, improving energy utilization efficiency. The self-defrosting module achieves low-energy defrosting without downtime by alternating operation of dual evaporators and coordinating with waste cooling and waste heat, ensuring continuous and stable operation of the system. The intelligent control module integrates data from the entire system and relies on machine learning to achieve dynamic collaborative control of multiple modules. Fault warning and self-repair functions improve the system's intelligence level, reduce manual operation and maintenance costs, and achieve multi-objective optimization of separation accuracy, energy consumption, and operational stability. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the overall workflow of the cryogenic condensation and ultra-low emission oil and gas recovery system of the present invention. Figure 2 This is a flowchart illustrating the pre-separation module of the present invention. Figure 3 This is a flowchart illustrating the operation of the cryogenic refrigeration module of the present invention. Figure 4 This is a flowchart illustrating the workflow of the waste cooling recovery module of this invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figures 1 to 4 As shown, this embodiment of the invention provides an ultra-low temperature condensation ultra-low emission oil and gas recovery system, which includes the following specific modules: The cryogenic refrigeration module employs a component adaptive gradient ratio mixed working fluid. The mixed working fluid is composed of neon, nitrogen, low-carbon alkanes, and hydrofluorocarbons, precisely proportioned according to real-time oil and gas components. The low-carbon alkanes are propane and butane in a 3:1 mass ratio, and the hydrofluorocarbons are R23 and R14 in a 2:1 mass ratio, adapting to dynamic changes in light and heavy hydrocarbons. Combined with a single-stage variable frequency compressor and a segmented regenerator, it achieves cryogenic refrigeration from -170℃ to -120℃, eliminating the need for a three-stage cascade refrigeration structure, simplifying system complexity, and improving operational reliability. This single-stage variable frequency compressor is a screw-type refrigeration compressor, suitable for mixed working fluids with a working pressure range of 0.1MPa~3.0MPa, a frequency conversion range of 30Hz~60Hz, a rated cooling capacity of 100kW~500kW, and can achieve stepless adjustment of cooling power according to the cooling temperature requirements. The compressor discharge temperature is controlled at 80℃~100℃, and it is equipped with a low-temperature lubricating oil circulation system, suitable for ultra-low temperature refrigeration conditions of -180℃.

[0018] The segmented regenerator consists of two sections: a low-temperature section and a medium-temperature section. Both sections use shell-and-tube heat exchangers made of copper. The low-temperature section operates at a temperature of -170℃ to -80℃, while the medium-temperature section operates at a temperature of -80℃ to 20℃. The overall heat exchange efficiency of the regenerator is ≥95%. The flow velocity of the working fluid within the regenerator is controlled at 0.8m / s to 1.2m / s, enabling gradient temperature regulation of the mixed working fluid and cold energy recovery.

[0019] The mass percentage range of each component in the mixed working fluid is as follows: neon 5%~15%, nitrogen 10%~20%, low-carbon alkanes 40%~60%, and hydrofluorocarbons 15%~25%. Among them, the low-carbon alkanes are propane and butane mixed in a mass ratio of 3:1, and the hydrofluorocarbons are R23 and R14 mixed in a mass ratio of 2:1. Each component can be dynamically adjusted within the above range according to the proportion of light hydrocarbons / heavy hydrocarbons in the oil and gas.

[0020] The online detection unit for oil and gas components is used to collect the proportion of light hydrocarbons and heavy hydrocarbons in the pre-separated oil and gas in real time. Light hydrocarbons include methane and ethane, while heavy hydrocarbons include propane and butane. The mass concentration of each component in the mixed working fluid is dynamically adjusted through an AI adaptive algorithm to match the cooling temperature with the oil and gas composition. When the proportion of light hydrocarbons is high, the ratio of low-boiling-point working fluids such as neon and nitrogen is increased to lower the cooling temperature to -150℃ to -170℃. When the proportion of heavy hydrocarbons is high, the ratio of high-boiling-point working fluids is increased to maintain the cooling temperature at -120℃ to -140℃, thereby reducing system energy consumption while ensuring the depth of cooling. The AI ​​adaptive algorithm takes as input real-time mass percentage data of light and heavy hydrocarbons in the pre-separated oil and gas collected by the online oil and gas component detection unit, and outputs real-time mass concentration adjustment values ​​of each component in the mixed working fluid, including neon, nitrogen, low-carbon alkanes, and hydrofluorocarbons. The algorithm uses a multivariate linear regression algorithm to achieve dynamic mapping between input and output through a preset component-cooling temperature-working fluid ratio association database, ensuring accurate matching between cooling temperature and oil and gas components.

[0021] The evaporator, the top condenser of the distillation column, and the bottom reboiler are integrated into a single composite heat exchanger. It adopts a high-efficiency heat exchange structure and an optimized design of irregularly shaped heat exchange tubes and fins. The irregularly shaped heat exchange tubes are made of corrosion-resistant alloy material, and the fins adopt a serrated structure to increase the heat exchange area, reduce cold energy loss, improve refrigeration efficiency and heat transfer efficiency, and provide an ultra-low temperature cold source for the system to meet the temperature requirements of oil and gas condensation and separation.

[0022] The integrated composite heat exchanger uses Hastelloy C276 heat exchange tubes with an inner diameter of 8mm~12mm, an outer diameter of 14mm~18mm, and a tube spacing of 20mm~25mm. The serrated fins are made of 304 stainless steel with a fin thickness of 0.3mm~0.5mm and a fin spacing of 4mm~6mm. The overall heat exchange area of ​​the heat exchanger is 200m²~500m², and the design pressure is 1.6MPa.

[0023] The pre-separation module utilizes the cold energy generated by the ultra-low temperature refrigeration module in a graded and stepped manner, extracting a portion of the medium- and low-temperature cold energy to achieve gradient low-temperature dehydration. Simultaneously, it receives upstream oil and gas feedstocks and integrates cyclone separation, electrostatic dust removal, and gradient low-temperature dehydration, achieving simultaneous removal of micro-oil mist (particle size ≤10μm), solid dust, and moisture from the oil and gas. The cyclone separation unit is a high-efficiency cyclone separation structure with a cylinder diameter of 300mm~800mm, a cylinder height of 1200mm~3200mm, and a processing oil and gas air volume range of 500m³ / h~5000m³ / h. It has a separation efficiency of ≥99% for solid dust with a particle size ≥5μm and a capture efficiency of ≥95% for micro-oil mist with a particle size ≤10μm. The cyclone velocity of oil and gas in the separator is controlled at 15m / s~20m / s.

[0024] The electrostatic dust removal unit adopts a low-temperature adaptable honeycomb electrode structure, and the electrode surface is coated with an anti-condensation coating. The anti-condensation coating is made of polytetrafluoroethylene, which is resistant to low temperatures and does not easily condense, effectively preventing low-temperature condensation from affecting the dust removal effect. At the same time, an electrode cleaning adaptive control is set to dynamically adjust the electric field strength according to the amount of dust accumulation. The amount of dust accumulation is detected in real time by a pressure sensor on the electrode surface. When the dust accumulation thickness is detected to be ≥2mm, the electric field strength gradually increases from the initial 30kV / m~40kV / m to 50kV / m~60kV / m, and continues for 10min~15min to complete the dust removal. After dust removal, the initial electric field strength is restored, thus achieving adaptive dust removal.

[0025] The low-temperature dehydration unit adopts a composite structure of gradient precooling and adsorption-assisted dehydration. It first cools to 5°C to remove most of the water, then cools to -20°C to remove trace amounts of free water, and finally achieves the dehydration target of ≤10ppm residual water through adsorption by modified molecular sieves. This prevents water from freezing and clogging the pipes after entering the ultra-low temperature condensation unit, and also avoids the impact of water on the accuracy of subsequent distillation separation. Cooling to 5°C can remove more than 90% of the free water in the oil and gas, and cooling to -20°C removes more than 95% of the remaining free water. After gradient precooling, the residual water content in the oil and gas is reduced to less than 500ppm, and finally, after adsorption by modified molecular sieves, the target of ≤10ppm residual water is achieved.

[0026] Modified molecular sieves are prepared using 3A molecular sieves as the matrix and modified by impregnation. The modifier is a 10%~15% (w / w) calcium chloride aqueous solution. After impregnation, the sieves are dried at 105℃~120℃ for 4h~6h to obtain modified molecular sieves. The liquid-solid ratio of molecular sieves to modifier is 3:1. The impregnation temperature is 60℃~80℃ and the impregnation time is 4h~6h. After drying, the modified molecular sieves are obtained. The static water adsorption capacity is ≥20wt% and can stably adsorb at a low temperature of -20℃.

[0027] The pre-separation module is also equipped with a pre-treated oil and gas purity detection unit, which is used to provide real-time feedback on impurity content. If impurities are detected to exceed the standard, a second cycle of pre-treatment is automatically triggered to ensure the cleanliness of the oil and gas entering the subsequent modules, providing clean oil and gas feedstock for the distillation and condensation module, and avoiding wear and blockage of various equipment in the system due to impurities.

[0028] The trigger thresholds for secondary pretreatment are: solid dust concentration ≥5mg / m³, oil mist content ≥10mg / m³, and water content ≥10ppm in the oil and gas. After triggering, the oil and gas will flow back to the inlet of the cyclone separation unit through the bypass pipeline, and then undergo the entire process of cyclone separation, electrostatic dust removal, and gradient low temperature dehydration again until the purity detection index is lower than the trigger threshold, and then be sent to the distillation and condensation module.

[0029] The distillation and condensation module receives the clean oil and gas delivered by the pre-separation module and uses the ultra-low temperature cold source provided by the ultra-low temperature refrigeration module to construct an integrated separation structure for ultra-low temperature condensation, staged distillation and distillation purification. It adopts composite packing adapted to the ultra-low temperature environment, using ceramic and metal composite packing, which is resistant to low temperature and anti-frost, can withstand ultra-low temperature environment below -170℃, is not easy to frost and has high separation efficiency. The composite packing is a composite Pall ring packing of ceramic and 316L stainless steel. The mass ratio of ceramic to 316L stainless steel is 1:2. The nominal diameter of the packing is 25mm~38mm, the height is 25mm~38mm, the packing wall thickness is 1.5mm~2mm, the surface is polished to prevent frost formation, the porosity is ≥95%, and the specific surface area is ≥150m² / m³.

[0030] An integrated condenser-evaporator is installed at the top of the tower, sharing the cold source with the evaporator of the refrigeration module to reduce cold energy loss. A low-temperature reboiler is installed at the bottom of the tower to utilize the heat recovered from the residual cold to achieve energy recycling. Two to three intermediate liquid collection sections are added in the middle of the tower to collect hydrocarbon components with different boiling points, so as to achieve the graded recovery of hydrocarbons with different boiling points. The distillation column adopts a vertical atmospheric distillation column structure. The column body is made of 316L stainless steel, with a column diameter of 500mm~1500mm and a total height of 8m~20m. It is divided into three sections according to function: condensation section, rectification section, and stripping section. The condensation section is 2m~4m high, the rectification section is 4m~12m high, and the stripping section is 2m~4m high. Two to three intermediate liquid collection sections are evenly distributed in the rectification section. The liquid collection section is equipped with a heat preservation layer and low temperature valves to prevent hydrocarbon components from re-vaporizing.

[0031] The low-temperature reboiler is a horizontal shell-and-tube structure. The heat exchange tubes are made of 316L stainless steel. The shell side carries the distillate from the distillation column, while the tube side carries a mixed heat exchange medium of residual heat and cold. The inner diameter of the heat exchange tubes is 10mm~14mm, the outer diameter is 16mm~20mm, the heat exchange area is 80m²~200m², the heat exchange efficiency is ≥85%, the design operating temperature is -80℃~50℃, and the operating pressure is 0.8MPa~1.5MPa.

[0032] After pre-separation, the oil and gas enter the rectification and condensation module. Under ultra-low temperature conditions, most of the heavy hydrocarbon components (boiling point ≥ 0℃) are liquefied and recovered through condensation. This condensation process achieves a liquefaction recovery rate of over 99.9% for heavy hydrocarbon components with a boiling point ≥ 0℃. Only trace amounts of heavy hydrocarbons enter the subsequent rectification section with the mixed gas. Combined with subsequent staged rectification processes, the overall recovery rate of heavy hydrocarbon components is ultimately ≥ 99.99%. The remaining mixture of light hydrocarbons and air enters the rectification section. Through staged rectification, the light hydrocarbon components are separated in stages. Different tower sections are controlled at different temperatures, and the temperature gradient between adjacent tower sections is controlled within the range of 5℃ to 10℃. High-boiling-point light hydrocarbons (propane, butane, boiling point -42℃~0℃) are condensed and recovered in the lower part of the rectification section, while low-boiling-point light hydrocarbons (methane, ethane, boiling point ≤ -42℃) enter the upper part of the rectification section. After further purification by the stripping unit, they are condensed and recovered, and the clean air is discharged through the top of the tower. Online detection units for oil and gas components are installed in each section of the distillation column to monitor the hydrocarbon component content in real time. The distillation temperature and reflux ratio are dynamically adjusted through AI algorithms to ensure the separation of light hydrocarbons from air. The NMHC concentration in the tail gas is less than 20 mg / m³, which is far better than the ultra-low emission requirements (≤30 mg / m³), thus improving the oil and gas recovery rate and resource utilization rate. The cold energy and waste heat generated during operation provide a source for the waste heat recovery module.

[0033] The AI ​​algorithm takes as input real-time hydrocarbon component content in each section of the distillation column, real-time NMHC concentration in the tail gas, and real-time temperature gradient data in the distillation column. The output is the temperature adjustment increment value and reflux ratio adjustment coefficient for each section of the distillation column. The algorithm takes the tail gas NMHC concentration <20mg / m³ as the core constraint and uses a PID control algorithm to dynamically correct the distillation parameters, ensuring deep separation of light hydrocarbons and air.

[0034] The self-defrosting module adopts a dual-evaporator alternating operation and residual cold and residual heat synergistic defrosting structure to ensure continuous separation process. It is equipped with two parallel ultra-low temperature evaporators, and the evaporators use high-efficiency heat exchange materials. The ultra-low temperature evaporator adopts a shell-and-tube structure. The heat exchange tubes are made of Hastelloy C276 material. The working fluid is mixed in the tube side and oil and gas in the shell side. The inner diameter of the heat exchange tubes is 6mm~10mm, the outer diameter is 12mm~16mm, the tube spacing is 18mm~22mm, the heat exchange area of ​​a single evaporator is 50m²~150m², the design working pressure is 1.0MPa~2.5MPa, and it can stably exchange heat in an ultra-low temperature environment of -180℃.

[0035] Equipped with an online frost thickness detection unit using ultrasonic detection technology, the system achieves a detection accuracy of up to 0.01mm. This unit monitors frost thickness in real time. When the frost thickness is ≥0.3mm, the intelligent control module triggers a frost warning. When the frost thickness continues to increase to ≥0.5mm, the system automatically switches the operating status of the two parallel ultra-low temperature evaporators to avoid energy waste caused by ineffective defrosting and ensure continuous and stable system operation. The ultrasonic detection unit uses an ultrasonic probe with a frequency of 2MHz~5MHz. The probe is installed 5mm~8mm outside the heat exchange tube of the evaporator. The ultrasonic emission interval is 5s~10s. The frost layer thickness is calculated by the time difference of the ultrasonic reflected wave. The detection range is 0~5mm. The detection error is ≤0.01mm in a low temperature environment of -180℃~0℃.

[0036] During defrosting, the low-temperature cold energy from the waste heat recovery module is mixed with the system's waste heat to form a mild heat exchange medium of 0~5℃. The frost-covered evaporator is then defrosted without temperature difference through the heat exchange coil, achieving defrosting without shutdown and with low energy consumption. This shortens the defrosting time, prevents the frost layer from affecting the transfer of cold energy and the flow of oil and gas, and reduces the problems of oil and gas leakage and efficiency reduction caused by shutdown for defrosting.

[0037] The duration of a single defrost cycle is controlled between 15 and 30 minutes. The energy supply for the defrost process is provided by a combination of residual cooling and system waste heat in a mass ratio of 7:3. The residual cooling is provided by the residual cooling storage unit, and the system waste heat is taken from the compressor heat dissipation and the waste heat of the distillation column. After the two heat exchange and mixing, the temperature is stabilized at 0℃ to 5℃. The evaporator is defrosted through the heat exchange coil. After defrosting, the evaporator can quickly return to the refrigeration working state.

[0038] The waste cooling recovery module recovers and utilizes the waste cooling and waste heat generated during the operation of various modules, including the ultra-low temperature refrigeration module, the distillation condensation module, and the self-defrosting module, constructing a comprehensive waste cooling and waste heat recovery system. The recovered waste cooling includes the low-temperature waste cooling of clean air discharged from the top of the distillation column, the low-temperature waste cooling of hydrocarbon condensation recovery, and the low-temperature waste cooling of the refrigeration module's regenerator. Simultaneously, it recovers waste heat generated during system operation, including compressor heat dissipation and distillation column waste heat. Through multi-stage high-efficiency heat exchangers, the recovered waste cooling and waste heat are reused in stages. The low-temperature waste cooling of clean air is used for oil and gas pre-cooling to replace part of the refrigeration load and reduce the refrigeration energy consumption of the pre-separation module. All multi-stage high-efficiency heat exchangers are plate heat exchanger structures. The first-stage heat exchanger is made of Hastelloy C276 material, suitable for ultra-low temperature conditions of -120℃ to -170℃, with heat exchange plate thickness of 0.8mm to 1.2mm. The second and third-stage heat exchangers are made of 316L stainless steel, with heat exchange plate thickness of 0.6mm to 1.0mm. The plates of the third-stage heat exchanger are treated with anti-corrosion coating. The heat exchange efficiency of all heat exchangers is ≥90%, and the pressure range is 0.6MPa to 1.6MPa.

[0039] The low-temperature waste cooling of hydrocarbon recovery is used for pre-cooling of mixed working fluid, thereby improving the efficiency of the refrigeration module. The low-temperature waste cooling of the refrigeration module regenerator is exchanged with the system waste heat through temperature difference. The energy grade of the low-temperature waste cooling is improved by the waste heat, forming a heating medium suitable for the reboiler at the bottom of the distillation column, providing it with heat. This can reduce the consumption of external heat sources, regulate the temperature gradient in the distillation column, and improve the separation accuracy. The classification principle of multi-stage heat exchangers is as follows: heat exchangers are divided into three stages according to energy grade and temperature gradient. The first-stage heat exchanger uses high-grade low-temperature waste cooling (-120℃~-170℃) to pre-cool the mixed working fluid. The second-stage heat exchanger uses medium-grade waste cooling (-20℃~5℃) to pre-cool the oil and gas. The third-stage heat exchanger uses low-grade waste cooling and system waste heat (0~5℃) to heat the reboiler at the bottom of the distillation column.

[0040] The waste cooling recovery module is also equipped with a waste cooling storage unit. This unit uses low-temperature phase change energy storage material as the low-temperature energy storage medium. It has high energy storage efficiency and stable release, realizing closed-loop reuse of waste cooling, improving energy utilization efficiency, reducing overall system energy consumption, reducing waste of cold and heat energy, and achieving a dual improvement in separation efficiency and energy utilization efficiency. The recovered cold energy provides a guarantee for the low-energy defrosting of the self-defrosting module.

[0041] The low-temperature phase change energy storage material is a composite phase change material of n-octadecane and expanded graphite, with a mass ratio of n-octadecane to expanded graphite of 95:5. The phase change temperature is -15℃ to -10℃, the latent heat of phase change is ≥200kJ / kg, the energy storage density is ≥300MJ / m³, the operating temperature range is -180℃ to 50℃, the number of cycles is ≥1000, and the cold energy release rate is adjustable.

[0042] The metering feedback module adopts a multi-parameter linkage metering, real-time data feedback and AI dynamic calibration mode. Sensors are installed at the top exhaust port of the distillation column, the oil and gas inlet, the recovery liquid outlet and each intermediate liquid collection section of the distillation column. The sensors use high-precision detection chips to monitor the NMHC concentration, oil and gas flow rate, temperature, pressure, recovery liquid flow rate and hydrocarbon component content in the tail gas in real time. The metering coefficient is dynamically corrected by AI algorithm to realize the measurement of recovery amount, emission amount and recovery rate of each component. The AI ​​algorithm takes as input multi-dimensional monitoring data collected in real time by sensors, including exhaust gas NMHC concentration, oil and gas flow rate, temperature, pressure, recovered liquid flow rate, and hydrocarbon component content in each section. The output is a metering coefficient correction value adapted to real-time operating conditions. By training on historical operating data, the algorithm establishes an operating parameter-metering error correlation model and dynamically calibrates the basic metering coefficients under different temperatures and pressures to improve metering accuracy.

[0043] The sensor types and accuracies adapted to each parameter are as follows: NMHC concentration is detected using a photoionization sensor with an accuracy of 0.1 mg / m³; oil and gas flow rate is detected using a vortex flow meter with an accuracy of ±0.5%; temperature is detected using a PT100 platinum resistance temperature sensor with an accuracy of ±0.1℃; pressure is detected using a diffused silicon pressure sensor with an accuracy of ±0.2%FS; recovered liquid flow rate is detected using a Coriolis mass flow meter with an accuracy of ±0.1%; and hydrocarbon component content is detected using a gas chromatograph sensor with an accuracy of 0.01%.

[0044] The monitoring data is fed back to the intelligent control module in real time, providing data basis for the dynamic adjustment of refrigeration temperature, distillation parameters (reflux ratio, temperature gradient), mixed working fluid ratio, and defrosting sequence. At the same time, it provides a basis for environmental protection acceptance, resource accounting and hydrocarbon graded recovery optimization, making it easier for staff to keep track of the system's operating status and resource recovery in real time.

[0045] The intelligent control module integrates the operating data of the ultra-low temperature refrigeration module, the pre-separation module, the distillation and condensation module, the self-defrosting module, the residual cold recovery module, and the metering feedback module, as well as the monitoring data of the metering feedback module. It collects the operating data of each module in real time through sensors, including refrigeration temperature, oil and gas flow rate, impurity content, frost layer thickness, emission concentration, and hydrocarbon component content in each section. Using machine learning algorithms, it realizes dynamic and coordinated control of each module, and constructs a three-dimensional coordinated control model with separation accuracy, energy consumption and operational stability as the core, to achieve multi-objective optimization. This machine learning model is constructed using a gradient boosting decision tree algorithm. The inputs are real-time operating data of each module: refrigeration temperature, oil and gas flow rate, impurity content, frost layer thickness, emission concentration, hydrocarbon component content in each section, and waste cooling and waste heat recovery. The outputs are mixed working fluid ratio adjustment parameters, refrigeration power value, evaporator working status switching signal, distillation column temperature gradient and reflux ratio adjustment value, and energy utilization path allocation instructions. The model uses a multi-objective optimization criterion with separation accuracy as the core (weight 0.45), energy consumption optimization as the key (weight 0.35), and operational stability as the foundation (weight 0.2) to achieve coordinated output of various control parameters.

[0046] For example: based on changes in oil and gas inlet flow rate and composition, the mixing ratio and refrigeration power are automatically adjusted to ensure that the refrigeration temperature matches the separation requirements; based on the frost layer thickness and distillation load, the evaporator operating status is automatically switched to avoid defrosting affecting separation efficiency; based on the hydrocarbon component content of each section, the temperature gradient and reflux ratio of the distillation column are automatically adjusted to improve the accuracy of staged recovery; based on the amount of waste cooling and waste heat recovered, the energy utilization path is dynamically allocated to achieve optimal energy consumption. The system is equipped with fault warning and self-repair functions, which can promptly detect problems such as pipe blockage, abnormal cooling, and decreased separation accuracy and issue audible and visual warnings. For faults such as minor frost and parameter deviation, it can automatically adjust relevant parameters to achieve self-repair, improve the reliability and intelligence of system operation, and reduce manual maintenance costs and the labor intensity of staff.

[0047] Minor faults refer to slight frost formation with a frost layer thickness of less than 1 mm, cooling temperature deviation of ≤5℃, and slight decrease in separation accuracy in the range of 20-25 mg / m³ for exhaust gas NMHC concentration. Serious malfunctions refer to issues such as pipe blockage ≥30%, refrigeration temperature deviation >10℃, and exhaust gas NMHC concentration >25mg / m³, which will only issue an early warning and prompt manual intervention.

[0048] The AI ​​algorithm for fault warning takes into account the deviation and trend of real-time operating parameters of each module. Using a preset fault characteristic threshold library, such as cooling temperature deviation > 5℃, exhaust gas NMHC concentration > 20mg / m³, and frost thickness ≥ 0.3mm, an anomaly detection algorithm is used to determine the fault type and level and trigger the corresponding warning. The AI ​​algorithm for self-repair takes into account the type of minor fault and parameter deviation value, and outputs targeted parameter adjustment commands, such as outputting compressor frequency adjustment value when cooling temperature deviation ≤ 5℃, and outputting defrost energy allocation value when there is slight frost, thus realizing automatic fault repair.

[0049] The audible and visual warning unit is installed in the system control cabinet and on-site operation terminal. Minor faults trigger a flashing yellow light combined with a low-frequency buzzer (500Hz, 1 second on, 2 seconds off). Serious faults trigger a constant red light combined with a high-frequency buzzer (800Hz, continuous sound). At the same time, the warning information is uploaded to the system background monitoring terminal, displaying the faulty module, fault type, and fault parameter deviation value, which facilitates maintenance personnel to quickly locate and handle the fault.

[0050] This invention also provides a method for recovering ultra-low emission oil and gas through cryogenic condensation, based on the above-described system, including the following specific steps: S1: For ultra-low temperature refrigeration, an adaptive gradient ratio of mixed working fluid is used, combined with a single-stage variable frequency compressor and segmented regeneration process. By online detection of oil and gas components and using AI algorithm to dynamically adjust the working fluid ratio, ultra-low temperature refrigeration of -170℃ to -120℃ is achieved. The evaporator and distillation heat exchange equipment are integrated into an integrated composite heat exchanger. S2: Pre-process the front-end oil and gas feedstock, utilize the cold energy generated by the ultra-low temperature refrigeration module in a graded and stepped manner, extract some medium and low temperature cold energy to achieve gradient low temperature dehydration, integrate cyclone separation, electrostatic dust removal and gradient low temperature dehydration functions, remove tiny oil mist, solid dust and moisture from the oil and gas, ensure the cleanliness of the oil and gas through purity detection, and trigger secondary pre-processing when impurities exceed the standard. S3: Perform distillation and condensation separation, utilize ultra-low temperature cold source to construct an integrated separation process, adopt low temperature resistant and anti-frost composite packing, and achieve graded recovery of hydrocarbons with different boiling points through staged distillation and stripping purification, monitor hydrocarbon components in real time and adjust operating parameters to ensure that the NMHC concentration in the tail gas is below 20mg / m³. S4: During operation, dual evaporators work alternately and waste cooling and heat are used for defrosting. The frost thickness is monitored in real time and the working state is switched adaptively to achieve defrosting with low energy consumption and no downtime. At the same time, waste cooling and waste heat from each process are recovered to build a closed-loop reuse system and achieve graded energy utilization through multi-stage heat exchange. S5: Through multi-parameter linkage metering and AI dynamic calibration, it monitors operating data and feeds it back to the intelligent control module. It uses machine learning algorithms to achieve coordinated control of various processes, and combined with fault warning and self-repair functions, it improves oil and gas recovery rate and system operation reliability.

[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A cryogenic condensation and ultra-low emission oil and gas recovery system, characterized in that, include: The ultra-low temperature refrigeration module uses a component adaptive gradient ratio mixed working fluid that can adapt to the dynamic changes of oil and gas components. It is paired with a single-stage variable frequency compressor and a segmented regenerator to achieve ultra-low temperature refrigeration. Through online detection of oil and gas components and dynamic adjustment of the working fluid ratio by AI algorithm, it matches the refrigeration requirements of different oil and gas components. The evaporator, the top condenser of the distillation column, and the bottom reboiler are integrated into an integrated composite heat exchanger. The pre-separation module, based on the cold energy provided by the cryogenic refrigeration module, integrates multiple pre-treatment functions to remove tiny oil mist, solid dust and trace moisture with a particle size ≤10μm from the oil and gas. Through purity detection and secondary pre-treatment mechanisms, it ensures the cleanliness of the oil and gas feedstock. The distillation and condensation module receives the pre-separated clean oil and gas, and uses the cold energy provided by the ultra-low temperature refrigeration module to construct an integrated separation structure. It adopts low-temperature resistant and anti-frost composite packing and realizes the graded recovery of hydrocarbons with different boiling points through staged distillation and stripping purification processes. It achieves the separation of light hydrocarbons and air by adjusting the operating parameters through online component detection and AI algorithm. The self-defrosting module adopts a combination structure of two parallel ultra-low temperature evaporators working alternately and waste cooling and waste heat working together for defrosting. It achieves adaptive switching of working status through online frost layer detection, realizing defrosting without shutdown. The waste cooling recovery module recovers the waste cooling and waste heat generated during the operation of each module, constructing a collaborative recovery and reuse closed loop, and realizing graded energy utilization through multi-stage heat exchangers; a waste cooling storage unit is set up to improve energy utilization efficiency and provide cold energy support for the self-defrosting module; The metering feedback module adopts a mode that combines multi-parameter linkage metering with AI dynamic calibration. It monitors key operating parameters of the system in real time through sensors, realizes the data metering of recovery and emission, and feeds the data back to the intelligent control module in real time. The intelligent control module integrates the operation and monitoring data of each module and uses machine learning algorithms to achieve dynamic and coordinated control of each module. It adjusts the operating parameters through a three-dimensional collaborative multi-objective optimization model with separation accuracy, energy consumption and operational stability as the core, and has fault early warning and self-repair functions.

2. The cryogenic condensation and ultra-low emission oil and gas recovery system according to claim 1, characterized in that, The ultra-low temperature refrigeration module has a refrigeration temperature range of -170℃ to -120℃. The online oil and gas component detection unit collects the proportion of light hydrocarbons and heavy hydrocarbons in the pre-separated oil and gas in real time. The AI ​​adaptive algorithm dynamically adjusts the mass concentration of each component in the mixed working fluid according to the component proportion. When the proportion of light hydrocarbons is high, the refrigeration temperature is reduced to -150℃ to -170℃, and when the proportion of heavy hydrocarbons is high, the refrigeration temperature is adjusted to -120℃ to -140℃. The integrated composite heat exchanger adopts a high-efficiency heat exchange structure. The irregularly shaped heat exchange tubes are made of corrosion-resistant alloy material, and the fins adopt a sawtooth structure to increase the heat exchange area and improve the heat exchange efficiency, providing a stable ultra-low temperature cold source for the system.

3. The cryogenic condensation and ultra-low emission oil and gas recovery system according to claim 2, characterized in that, The pre-separation module integrates cyclone separation, electrostatic dust removal, and gradient low-temperature dehydration into a triple pretreatment process, achieving simultaneous removal of impurities and moisture from oil and gas. The electrostatic dust removal unit adopts a low-temperature adaptable honeycomb electrode structure and is equipped with an electrode cleaning adaptive control function. The low-temperature dehydration unit adopts a composite structure of gradient precooling and adsorption-assisted dehydration to remove most of the moisture and trace amounts of residual moisture from the oil and gas. The purity detection unit of the pre-separation module provides real-time feedback on the impurity content, and automatically triggers a secondary cycle pretreatment when the impurities exceed the standard.

4. The cryogenic condensation and ultra-low emission oil and gas recovery system according to claim 3, characterized in that, The integrated separation structure of the distillation and condensation module includes an integrated condenser-evaporator at the top of the column and a low-temperature reboiler at the bottom of the column. An intermediate liquid collection section is provided in the middle of the column to collect hydrocarbon components with different boiling points. After pre-separation, the oil and gas enter the distillation and condensation module. Most of the heavy hydrocarbons are recovered through condensation. The remaining light hydrocarbons and air mixture are purified by staged distillation and stripping to achieve staged recovery of light hydrocarbons. Clean air is discharged from the top of the column. The online oil and gas component detection unit monitors the hydrocarbon component content in real time, and the AI ​​algorithm dynamically adjusts the operating parameters to ensure that the NMHC concentration in the tail gas is below 20 mg / m³.

5. The cryogenic condensation and ultra-low emission oil and gas recovery system according to claim 4, characterized in that, The two parallel ultra-low temperature evaporators of the self-defrosting module adopt high-efficiency heat exchange materials. The online frost layer thickness detection unit monitors the frost layer status in real time. When the set threshold is reached, the evaporator working state is automatically switched to achieve adaptive switching between evaporator working and defrosting states. The defrosting process utilizes the cold energy recovered by the waste heat recovery module and the system waste heat to achieve defrosting without downtime and with low energy consumption.

6. The cryogenic condensation and ultra-low emission oil and gas recovery system according to claim 5, characterized in that, The waste cooling recovery module constructs a full-process waste cooling and waste heat collaborative recovery system, recovering the waste cooling and waste heat generated by each module, and realizing energy staged reuse through multi-stage high-efficiency heat exchangers, which are used for oil and gas precooling, mixed working fluid precooling and distillation column bottom reboiler heating respectively; the waste cooling storage unit realizes closed-loop reuse of waste cooling, providing cold energy guarantee for the self-defrosting module.

7. The cryogenic condensation and ultra-low emission oil and gas recovery system according to claim 6, characterized in that, The metering feedback module is equipped with sensors at key locations in the system to monitor in real time the NMHC concentration in the exhaust gas, oil and gas flow rate, temperature, pressure, recovery liquid flow rate, and hydrocarbon component content in each section. The metering coefficient is dynamically corrected through AI algorithms to measure the recovery amount, emissions, and recovery rate of each hydrocarbon component. The monitoring data is fed back to the intelligent control module in real time to provide data support for system parameter adjustment, environmental acceptance, and resource accounting.

8. The cryogenic condensation and ultra-low emission oil and gas recovery system according to claim 7, characterized in that, The intelligent control module collects real-time operating data from each module through sensors and uses machine learning algorithms to construct a three-dimensional collaborative control model with separation accuracy, energy consumption, and operational stability as its core, thereby achieving dynamic collaboration and multi-objective optimization among the modules. It automatically adjusts the mixing ratio, refrigeration power, and distillation parameters according to the oil and gas intake components and intake flow rate, and dynamically switches the evaporator state and allocates energy utilization paths according to the frost layer thickness and residual heat recovery amount. The fault warning and self-repair function can detect system anomalies and issue warnings, and automatically adjust parameters to repair minor faults.

9. A method for ultra-low emission oil and gas recovery through cryogenic condensation, based on the system described in claim 8, characterized in that, The specific steps include the following: S1: It adopts a component adaptive gradient ratio mixed working fluid, combined with a single-stage variable frequency compressor and segmented regenerative process. By detecting the oil and gas components online and using AI algorithms to dynamically adjust the working fluid ratio, it can achieve ultra-low temperature refrigeration of -170℃ to -120℃, and use an integrated composite heat exchanger to provide a cold source. S2: Relying on the cold energy provided by the ultra-low temperature refrigeration module, the front-end oil and gas raw materials are subjected to cyclone separation, electrostatic dust removal and gradient low temperature dehydration pretreatment to remove impurities and moisture. The purity of the oil and gas is ensured through purity testing. When the impurities exceed the standard, secondary pretreatment is triggered. S3: An integrated separation process is constructed using an ultra-low temperature cold source. Low-temperature resistant and anti-frost composite packing is used. Hydrocarbons with different boiling points are recovered in stages through staged distillation and stripping purification. Hydrocarbon components are detected in real time and operating parameters are adjusted to ensure that the NMHC concentration in the tail gas is below 20 mg / m³. S4: It adopts a dual-evaporator alternating operation and waste heat and waste cooling synergistic defrosting mode, monitors the frost layer thickness in real time and adaptively switches the working state to achieve non-stop low-energy defrosting; at the same time, the waste heat and waste cooling generated in the whole process of the system are synergistically recovered through the waste heat recovery module to build a closed-loop reuse system and realize energy graded utilization through multi-stage heat exchange. S5: By monitoring the operation data of the multi-parameter linkage metering and AI dynamic calibration monitoring system, the system feeds the data back to the intelligent control module. Machine learning algorithms are used to achieve coordinated control of various processes. Combined with fault warning and self-repair functions, the system improves the oil and gas recovery rate and the reliability of system operation.

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