Absorption condensation coupled oil and gas recovery method and apparatus

Abstract

The application discloses an absorption and condensation coupled oil gas recovery method and device, relates to the technical field of energy saving and environmental protection, and solves the problems of low efficiency and high energy consumption of the existing oil gas recovery process. The absorption and condensation process is coupled, a refrigerant evaporation unit is integrated in the absorption tower, the condensation and absorption processes are coupled to improve the recovery efficiency, a refrigerant condensation unit is integrated in the desorption tower, the condensation heat energy of the refrigeration cycle is recovered to heat the rich absorbent, and the operation energy consumption is reduced. Through switching of the refrigerant circulation direction, the absorption tower and the desorption tower are alternately operated, frost blocking is avoided, and the stability of the device is improved. The device comprises an air inlet precooling unit, a refrigeration cycle unit, an absorption tower and a vacuum desorption unit, can automatically adjust process parameters to realize intelligent operation, can be flexibly and rigidly adjusted to adapt to different working conditions, can be expanded and combined with multiple processes, is also applicable to the separation and recovery of VOCs, CO2 and other gases, has the characteristics of high efficiency and energy saving, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of energy conservation and environmental protection technology, specifically to a method and apparatus for absorption and condensation coupled oil and gas recovery. Background Technology

[0002] In the fields of oil and gas emissions, such as oil depots, gas stations, and oil transportation, air pollutant emission standards are constantly being updated, placing higher demands on the emission concentration control and treatment efficiency of oil and gas processing equipment. Currently, the mainstream oil and gas processing methods in the industry mainly include absorption, condensation, adsorption, membrane separation, catalytic combustion, and integrated processing technologies combining multiple methods. Among these, absorption is widely used in the pretreatment of oil and gas recovery in large-scale facilities such as oil depots due to its large processing capacity and significant economic cost advantages. Condensation, with its liquefaction separation characteristics, is often combined with other processes for the precise recovery of oil and gas components. Both are commonly used core technologies in the field of oil and gas recovery.

[0003] Existing absorption-based oil and gas recovery technologies suffer from significant efficiency shortcomings. Used alone, they struggle to meet current stringent emission standards and are typically only used as a pretreatment step in combination with other processes such as adsorption. Furthermore, to improve absorption efficiency, the absorbent requires pre-cooling, and the desorption and regeneration of the absorbent-rich material necessitates additional heating and a vacuum environment. The pre-cooling and heating units become the main energy-consuming components of absorption processes, resulting in high energy costs. While condensation methods can achieve oil and gas separation through low-temperature liquefaction, they require extremely low condensation temperatures for effective recovery of low-boiling-point light oil and gas components, significantly increasing refrigeration energy consumption. Therefore, they cannot be used alone as a high-efficiency, low-energy-consumption core process. Neither method, whether used alone or in simple combinations, can effectively balance processing efficiency and energy consumption control.

[0004] The combined absorption and condensation recovery process is relatively rare in the industry, and existing combined processes still suffer from insufficient energy utilization and poor process synergy. On the one hand, absorption and condensation are mostly simple processes superimposed, failing to achieve deep process integration and thus failing to leverage their synergistic effects, resulting in limited improvement in oil and gas recovery efficiency. On the other hand, the condensation unit in existing processes, whether used alone or in combination, relies solely on external cold sources or refrigerant recycling to utilize cooling capacity. The large amount of high-temperature condensation heat generated after refrigerant compression during the refrigeration cycle is not effectively recovered and utilized, leading to serious energy waste and further increasing the overall energy consumption of the unit. Furthermore, traditional coupled processes are prone to problems such as frost and blockage in the absorption tower, affecting the stability of unit operation. Therefore, there is an urgent need for an oil and gas recovery technology solution that can achieve deep coupling of absorption and condensation processes, efficient energy recovery, and stable operation.

[0005] Therefore, an absorption-condensation coupled oil and gas recovery method and device are proposed to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide an absorption-condensation coupled oil and gas recovery method and apparatus to solve the following problems existing in the prior art: (1) This solution addresses the problem that the recovery efficiency of existing oil and gas recovery processes is insufficient to meet high emission standards when absorption and condensation methods are used alone or in simple combinations. Traditional absorption methods have low recovery efficiency, and condensation methods require extremely low temperatures for the recovery of low-boiling-point light oil and gas components. Furthermore, the two methods often involve simple overlapping processes, failing to achieve deep process coupling and thus failing to leverage synergistic effects. This solution integrates a refrigerant evaporation unit into the absorption tower, coupling the condensation and absorption processes. By utilizing low temperatures to improve the absorption efficiency of the absorbent, this solution adapts to the recovery needs of different oil and gas components, significantly improving the overall oil and gas recovery efficiency and meeting the latest emission standards.

[0007] (2) Solve the problem of insufficient energy utilization and high overall operating energy consumption in existing oil and gas recovery processes. Traditional absorption methods require a large amount of energy for precooling and heating desorption. The refrigeration cycle only utilizes the cooling capacity of the refrigerant, and the high-temperature and high-pressure refrigerant condensation heat generated after compression by the compressor is directly wasted. Moreover, there is no effective heat recovery and cascade utilization design. This solution integrates a refrigerant condensation unit in the desorption tower to recover the condensation heat energy of the refrigeration cycle for heating the rich absorbent to complete desorption. At the same time, through multi-stage heat exchange between the rich and lean absorbents and the oil and gas to be treated, the loss of cooling capacity and heat is reduced, achieving efficient energy recovery and utilization, and significantly reducing the overall operating energy consumption of the unit.

[0008] To achieve the above objectives, the present invention provides the following technical solution: The principle of this technical solution is to use dual absorption towers coupled to the evaporation and condensation units of the refrigeration process, respectively. During operation, one tower is an absorption tower, which integrates the evaporation unit for refrigerant circulation, coupling the condensation and absorption processes to fully utilize cold energy and improve oil and gas recovery efficiency. The other tower is a desorption tower, which integrates the condensation unit for refrigerant circulation. It utilizes the heat energy of the high-temperature, high-pressure refrigerant after compression to heat the desorbed absorbent, recovering the heat energy of the refrigeration cycle and reducing the operating energy consumption of the device. By switching the refrigerant circulation direction, the condensation and evaporation units switch between each other, correspondingly switching the absorption and desorption operation modes of the two towers, operating alternately to improve the stability of the device operation.

[0009] The present invention provides a condensation absorption coupled oil and gas recovery method and apparatus, comprising the following steps: Step 1. Pre-cooling: The oil and gas to be treated are pre-cooled by exchanging heat with the low-temperature rich absorbent after absorbing the oil and gas in the first inlet heat exchanger E1 and the second inlet heat exchanger E2, respectively, to remove heavier hydrocarbon components and water. Step 2. Absorption: The absorbent is condensed by the tray S1 of the first integrated refrigerant evaporation / condensation unit and the tray S2 of the second integrated refrigerant evaporation / condensation unit, or by the packing layer S3, the packing layer S4, the packing layer S5, and the packing layer S6 of the first integrated refrigerant evaporation / condensation unit and the second integrated refrigerant evaporation / condensation unit. After condensation and absorption, the absorbent rich in oil and gas comes into counter-current contact with the pre-cooled oil and gas to absorb the oil and gas. After absorbing the oil and gas, the absorbent rich in oil and gas exchanges heat with the oil and gas to be treated and the lean absorbent in sequence and then goes to the desorption tower. The oil and gas to be treated is discharged after condensation and absorption to meet the standards. Step 3. Desorption: The rich absorbent is heated by the tray S1 of the first integrated refrigerant evaporation / condensation unit and the tray S2 of the second integrated refrigerant evaporation / condensation unit, or by the packing layer S3, the packing layer S4, the packing layer S5, and the packing layer S6 of the first integrated refrigerant evaporation / condensation unit, and the absorbed oil and gas is desorbed under vacuum. The desorbed lean absorbent exchanges heat with the rich absorbent and the exhaust gas outside the absorption tower in sequence and then goes to the absorption tower. The desorbed oil and gas goes to the oil and gas recovery tank. Step 4. Refrigeration Cycle: Low-temperature, low-pressure refrigerant enters the refrigerant evaporation units in the lower part of the absorption tower, specifically in the trays S1 and S2 of the first and second integrated refrigerant evaporation / condensation units, or in the packing layers S3, S4, S5, and S6 of the first, second, third, and fourth integrated refrigerant evaporation / condensation units. After vaporizing through heat exchange with the absorbent, the refrigerant exits the absorption tower from the upper part and enters the refrigeration compressor C1 unit, where it is compressed into a high-temperature, high-pressure gas and exits from the desorption tower. The refrigerant enters the upper middle section of the first integrated refrigerant evaporation / condensation unit in tray S1 and the second integrated refrigerant evaporation / condensation unit in tray S2, or in the packing layers S3, S4, S5, and S6 of the first, second, third, and fourth integrated refrigerant evaporation / condensation units. After the refrigerant exchanges heat with the rich absorbent and condenses into a medium-temperature, high-pressure refrigerant, it exits the desorption tower from the lower middle section and enters the throttling device D1 to reduce its pressure, becoming a low-temperature, low-pressure refrigerant. It then re-enters the absorption tower from the bottom, completing the refrigeration cycle. Step 5. Tower switching operation: The absorption tower and desorption tower have the same structure. The refrigerant circulation direction is switched by the four-way valve V19, so that the refrigerant evaporation unit integrated in the absorption tower is switched to the condensation unit, and the refrigerant condensation unit integrated in the desorption tower is switched to the evaporation unit, thereby realizing the switching of the operation mode of the absorption tower and the desorption tower.

[0010] Preferably, steps 1-5 are implemented through an automatic control system that automatically optimizes and adjusts the spraying volume of absorbent, the replenishment and discharge volume of absorbent, the condensation temperature, the desorption temperature, and the desorption vacuum degree in response to fluctuations in the concentration and component parameters of the oil and gas to be treated, thereby achieving intelligent and energy-saving operation.

[0011] A condensation-absorption coupled oil and gas recovery device includes an inlet precooling unit, a refrigeration cycle unit, an absorption tower unit, a vacuum desorption unit, and valves, connecting pipes, measuring instruments, and a control unit assembly. The inlet precooling unit is connected to the bottom of both the absorption tower and the desorption tower. The compression process section of the refrigeration cycle unit, after passing through a four-way valve V19, is connected to the evaporation and condensation units integrated in the upper middle part of the absorption tower and the desorption tower, respectively, within the first tray tower T1, the second tray tower T2, or the first packed tower T3, and the second packed tower T4. The throttling process section of the refrigeration cycle unit is connected to the lower middle part of the absorption tower and the desorption tower, respectively, within the evaporation and condensation units integrated in the first tray tower T1, the second tray tower T2, or the first packed tower T3, and the second packed tower T4. The exhaust outlet at the top of the absorption tower is connected to vacuum pump P3 and the first liquid outlet heat exchanger E4 and the second liquid outlet heat exchanger E5, respectively. The liquid inlet at the bottom of the absorption tower is connected to the bottom of the desorption tower through the first liquid inlet heat exchanger E1, the second liquid inlet heat exchanger E3, the first absorbent pump P1, and the second absorbent pump P2. The absorbent-rich outlet at the bottom of the absorption tower is connected to the liquid inlet at the bottom of the desorption tower through the first absorbent pump P1, the second absorbent pump P2, the first liquid inlet heat exchanger E1, and the second liquid inlet heat exchanger E3. The connections between the desorption tower and the absorption tower are one-to-one. Vacuum pump P3 is connected to the exhaust outlets of both the absorption tower and the desorption tower. The valves, connecting pipes, measuring instruments, and control unit assemblies are connected to each unit of the device to realize process flow and automated control.

[0012] Preferably, the pre-cooling unit includes a pre-cooling condenser, a separator G1, valves, connecting pipes, measuring instruments, and a control unit assembly. The inlet direction is switched according to the operating mode of the absorption tower and the desorption tower. When the switching operation begins, the oil and gas discharged from the top of the absorption tower and the desorbed oil and gas discharged from the desorption tower are first mixed with the oil and gas to be treated and then re-enter the absorption tower for further treatment. When the oil and gas discharged from the top of the absorption tower reaches the emission standard, the discharged oil and gas and the desorbed oil and gas are directly discharged, completing the switching operation of the absorption tower and the desorption tower.

[0013] Preferably, the refrigeration cycle unit includes a refrigeration compressor C1, a four-way valve V19, a tray S1 of the first integrated refrigerant evaporation / condensation unit and a tray S2 of the second integrated refrigerant evaporation / condensation unit or a packing layer S3 of the first integrated refrigerant evaporation / condensation unit, a packing layer S4 of the second integrated refrigerant evaporation / condensation unit, a packing layer S5 of the third integrated refrigerant evaporation / condensation unit, and a packing layer S6 of the fourth integrated refrigerant evaporation / condensation unit. The refrigerant condensing unit, throttling device D1, valves, connecting pipes, measuring instruments, and control unit components are located in the packing layer S5 of the third integrated refrigerant evaporation / condensation unit and the packing layer S6 of the fourth integrated refrigerant evaporation / condensation unit. The refrigerant circulation direction is changed by a four-way valve V19 and a one-way valve connected in parallel with the throttling unit, switching the operating modes of the absorption tower and desorption tower. Based on the composition and concentration fluctuations of the oil and gas to be treated, the refrigeration temperature in the absorption tower and the desorption temperature in the desorption tower are adjusted within a certain range, and coupled with the absorption process adjustment of the absorbent spray volume and desorption vacuum degree to achieve flexible adjustment of the oil and gas recovery process. Based on the oil and gas recovery efficiency and the recovery requirements of light oil and gas components, different specifications of refrigeration cycle units are selected and coupled with the absorption process to achieve rigid adjustment of the oil and gas recovery process.

[0014] Preferably, the absorption tower unit adopts a dual-tower alternating operation mode, with the two towers being either a first tray tower T1 and a second tray tower T2, or a first packed tower T3 and a second packed tower T4, and having identical structures. When one tower is performing absorption operation, the other tower is performing desorption operation. The absorption tower contains the tray S1 of the first integrated refrigerant evaporation / condensation unit and the tray S2 of the second integrated refrigerant evaporation / condensation unit, or the packing layer S3 of the first integrated refrigerant evaporation / condensation unit, the packing layer S4 of the second integrated refrigerant evaporation / condensation unit, and the packing layer S4 of the third integrated refrigerant evaporation / condensation unit. The material layer S5 and the packing layer S6 of the fourth integrated refrigerant evaporation / condensation unit are equipped with a heat insulation layer on the tower shell. By controlling and switching the gas inlet direction, refrigeration cycle direction, and absorbent cycle direction, the switching operation of the absorption tower and desorption tower can be realized. According to the composition and concentration fluctuations of the oil and gas to be treated, the process of automatically adjusting the absorbent spray volume in the absorption tower is coupled with the adjustment of the temperature parameters of the refrigeration cycle unit to realize flexible adjustment of the oil and gas recovery process. According to the oil and gas recovery efficiency and the recovery requirements of light oil and gas components, absorption towers and desorption towers of different specifications are selected and coupled with the refrigeration cycle unit to realize rigid adjustment of the oil and gas recovery process.

[0015] Preferably, when the absorption tower is a first tray tower T1 and a second tray tower T2, trays are evenly arranged in the first tray tower T1 and the second tray tower T2. Each tray integrates a refrigerant evaporation unit / condensation unit. The evaporation unit is integrated into the upper surface, hollow layer, or lower surface of the tray, and is designed as a single unit with the tray, increasing the heat exchange area while reducing space occupation. The number of tray layers is adjusted according to process requirements. When the absorption tower is switched to a desorption tower, the refrigerant evaporation unit on the tray is switched to a refrigerant condensation unit. The tray tower mainly includes a first mist eliminator H1 and a first absorbent distributor F1. The first integrated refrigerant evaporation / condensation unit tray S1 and the second integrated refrigerant evaporation / condensation unit tray S2 integrate the refrigerant evaporation / condensation unit structure, including a first refrigerant inlet / outlet S101, a second refrigerant inlet / outlet S102, a tray S103 and a refrigerant flow pipeline S104. The refrigerant flow pipeline S104 is embedded in the tray S103, which can increase the heat exchange area of ​​the refrigerant pipeline and improve the heat exchange effect by utilizing the tray.

[0016] Preferably, when the absorption tower is a first packed tower T3 and a second packed tower T4, the first packed tower T3 and the second packed tower T4 are uniformly provided with packing layers. The packing layers are provided with a first integrated refrigerant evaporation unit / condensation unit packing layer S3, a second integrated refrigerant evaporation unit / condensation unit packing layer S4, a third integrated refrigerant evaporation unit / condensation unit packing layer S5, and a fourth integrated refrigerant evaporation unit / condensation unit packing layer S6. The packing layer structure adopts regular packing or random packing. The evaporation unit is filled between the packing layers or designed integrally with the packing layer to increase the heat exchange area. The number and height of the packing layers are adjusted according to the process requirements. When the absorption tower is switched to a desorption tower, the refrigerant evaporation unit on the packing layer is switched to a refrigerant condensation unit.

[0017] Preferably, the desorption tower has the same structure as the absorption tower, and automatically switches to absorption tower when the absorption tower switches to desorption tower. The top of the desorption tower is connected to the vacuum pump P3, which automatically adjusts the desorption vacuum and the refrigerant temperature of the condensing unit in the first integrated refrigerant evaporation / condensation unit tray S1 and the second integrated refrigerant evaporation / condensation unit tray S2 or the packing layer S3, the second integrated refrigerant evaporation / condensation unit packing layer S4, the third integrated refrigerant evaporation / condensation unit packing layer S5 and the fourth integrated refrigerant evaporation / condensation unit packing layer S6 according to the parameter changes of the inlet rich absorbent, so as to meet the desorption requirements of the rich absorbent.

[0018] Preferably, the low-temperature rich absorbent after absorption and condensation in the absorption tower is pressurized by the first absorbent pump P1 and the second absorbent pump P2, and first exchanges heat with the inlet oil and gas to be treated in the first inlet heat exchanger E1 and the second inlet heat exchanger E3, and then enters the lean and rich absorbent heat exchanger E2 to exchange heat with the lean absorbent; the desorbed lean absorbent in the desorption tower is pressurized by the first absorbent pump P1 and the second absorbent pump P2, and first enters the lean and rich absorbent heat exchanger E2 to exchange heat with the low-temperature rich absorbent, and then exchanges heat again with the low-temperature qualified exhaust gas in the absorption tower in the first outlet heat exchanger E4 and the second outlet heat exchanger E5.

[0019] Preferably, the vacuum desorption unit includes a vacuum pump P3, valves, connecting pipes, measuring instruments, and a control unit assembly. The vacuum pump P3 is connected to both the absorption tower and the desorption tower. During normal operation, the pipe connecting to the absorption tower is shut off by the valve, and only the desorption tower is connected for rich absorbent desorption. When the absorption tower and desorption tower are switched, the vacuum pump P3 automatically switches to the desorption tower after switching via the control unit. The vacuum pump P3 is coupled with the refrigerant temperature regulation of the condensing unit in the first integrated refrigerant evaporation / condensation unit (plate S1) and the second integrated refrigerant evaporation / condensation unit (plate S2) or the packing layer S3, the second integrated refrigerant evaporation / condensation unit (packing layer S4), the third integrated refrigerant evaporation / condensation unit (packing layer S5), and the fourth integrated refrigerant evaporation / condensation unit (packing layer S6) according to the parameter changes of the rich absorbent, automatically adjusting the desorption vacuum level to reduce operating energy consumption while satisfying the rich absorbent desorption effect.

[0020] Preferably, the device can be equipped with adsorption, membrane separation, and catalytic combustion processes to form a multi-stage integrated oil and gas recovery process; in addition to oil and gas recovery, the device can also be used for the separation and recovery of organic waste gas VOCs, CO2, SO2 and other gases.

[0021] Compared with the prior art, the absorption-condensation coupled oil and gas recovery method and apparatus provided by the present invention have the following beneficial effects: I. Process coupling enables synergistic improvement in energy efficiency, breaking through the bottleneck of single processes; This solution deeply couples the absorption and condensation processes, integrating a refrigerant evaporation unit into the absorption tower. This allows the condensation and absorption processes to occur simultaneously, significantly improving the absorption efficiency of the absorbent for oil and gas in low-temperature environments. This solves the problems of low recovery efficiency and difficulty in meeting standards when used alone in traditional absorption methods. At the same time, it abandons the simple superposition of the two processes, leveraging the synergistic effect of condensation and absorption. By adjusting the refrigeration temperature, the number of trays, or the packing height, it can adapt to the recovery requirements of different oil and gas components, meeting higher standards for oil and gas emission concentrations and treatment efficiency.

[0022] II. Heat energy recovery and utilization reduce operating energy consumption and achieve energy-saving operation; The proposed solution integrates a refrigerant condensation unit into the desorption tower, fully recovering the condensation heat energy of the high-temperature, high-pressure refrigerant after compression in the refrigeration cycle. This heat energy is then used to heat the rich absorbent to complete desorption, replacing the traditional method of providing an additional heat source for the desorption of the rich absorbent. This also solves the problem of existing refrigeration cycles only utilizing cooling capacity while wasting condensation heat. At the same time, the multi-stage heat exchange design between the rich absorbent, the oil and gas to be treated, and the lean absorbent further reduces the loss of cooling and heating capacity, significantly lowering the overall energy consumption cost of the unit during operation.

[0023] 3. The alternating operation of the two towers improves the stability and continuity of the unit's operation; The absorption tower and desorption tower adopt the same structural design. By switching the refrigerant circulation direction, the functions of the evaporation unit and the condensation unit can be interchanged, thereby completing the switching between absorption and desorption operation modes of the two towers. This design effectively avoids problems such as pipeline blockage and excessive pressure difference caused by condensation and frosting in the absorption tower in traditional absorption-condensation coupling processes. Moreover, the switching process can be completed by an automatic control system. Oil and gas that do not meet the standards in the initial stage of switching can be mixed with the oil and gas to be treated and reprocessed, ensuring the continuity and stability of the unit's operation and making it suitable for long-term continuous industrial operation.

[0024] IV. It combines flexible and rigid adjustments, offering strong adaptability and good expandability; The device can flexibly adjust parameters such as absorbent spray volume, condensation temperature, desorption temperature, and desorption vacuum degree according to the concentration and composition fluctuations of the oil and gas to be treated, through an automatic control system. This allows for adaptation to changes in operating conditions without significant equipment modifications. Simultaneously, different specifications of refrigeration cycle units, absorption towers, and desorption towers can be coupled based on the oil and gas recovery efficiency and the recovery requirements of light oil and gas components to achieve rigid process adjustment. Furthermore, this device can be supplemented with adsorption and membrane separation processes to form a multi-stage integrated oil and gas recovery system. Besides oil and gas recovery, it can also be applied to the separation and recovery of other gases such as organic waste gas, CO2, and SO2, making it suitable for a wide range of applications. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a condensation absorption coupled oil and gas recovery device using a tray tower according to the present invention; Figure 2 This is a schematic diagram of the structure of the tray tower of the present invention in a semi-section state; Figure 3 This is an exploded internal structural diagram of the tray of the first integrated refrigerant evaporation / condensation unit of the present invention. Figure 4 This is a schematic diagram of a condensation absorption coupled oil and gas recovery device using a packed tower according to the present invention; Figure 5 This is a schematic diagram of the packed tower structure in a semi-sectional state according to the present invention; Figure 6 This is a schematic diagram of the internal structure of the packing layer of the integrated refrigerant evaporation / condensation unit in the packed tower of the present invention.

[0026] In the picture: C1, Refrigeration compressor; D1, Throttling device; E1, First inlet heat exchanger; E2, Lean and rich absorbent heat exchangers; E3, Second inlet heat exchanger; E4, First outlet heat exchanger; E5, Second outlet heat exchanger; F1, First absorbent distributor; F2, Second absorbent distributor; F3, Third absorbent distributor; F4, Fourth absorbent distributor; F5, First absorbent re-distributor; F6, Second absorbent re-distributor; G1, Separator; H1, First mist eliminator; H2, Second mist eliminator; P1, First absorbent pump; P2, Second absorbent pump; Two absorbent pumps; P3, vacuum pump; T1, first tray tower; T2, second tray tower; T3, first packed tower; T4, second packed tower; S1, tray of the first integrated refrigerant evaporation / condensation unit; S2, tray of the second integrated refrigerant evaporation / condensation unit; S3, packing layer of the first integrated refrigerant evaporation / condensation unit; S4, packing layer of the second integrated refrigerant evaporation / condensation unit; S5, packing layer of the third integrated refrigerant evaporation / condensation unit; S6, packing layer of the fourth integrated refrigerant evaporation / condensation unit. V1, First valve; V2, Second valve; V3, Third valve; V4, Fourth valve; V5, Fifth valve; V6, Sixth valve; V7, Seventh valve; V8, Eighth valve; V9, Ninth valve; V10, Tenth valve; V11, Eleventh valve; V12, Twelfth valve; V13, Thirteenth valve; V14, Fourteenth valve; V15, Fifteenth valve; V16, Sixteenth valve; V17, Seventeenth valve; V18, Eighteenth valve; V19, Four-way valve; S101, First refrigerant inlet / outlet; S102, Second refrigerant inlet / outlet; S103, Tray; S104, Refrigerant flow line; S301, Third refrigerant inlet / outlet; S302, Fourth refrigerant inlet / outlet; S303, Packing layer; S304, Refrigerant flow line. Detailed Implementation

[0027] 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0029] Example 1, please refer to Figures 1 to 6 As shown: To solve the problems mentioned in the technical solution, such as Figure 1 The image shows a condensation absorption coupled oil and gas recovery device using a tray tower. Figure 2 The diagram shows the structure of the tray tower. The first tray tower T1 and the second tray tower T2 are mainly composed of the first mist eliminator H1, the first absorbent distributor F1, and the tray S1 of the first integrated refrigerant evaporation / condensation unit. Figure 3 The specific structure of the tray S1 of the first integrated refrigerant evaporation / condensation unit includes a first refrigerant inlet / outlet S101, a second refrigerant inlet / outlet S102, a tray S103, and a refrigerant flow pipeline S104. The refrigerant flow pipeline S104 is embedded inside the tray S103. The heat exchange area of ​​the refrigerant pipeline can be increased by means of the tray structure. Compared with the independent condensation unit, the heat exchange area can be increased by 2 to 5 times depending on the number of trays and the tray structure design, thereby significantly improving the heat exchange effect.

[0030] When the first tray T1 is used as an absorber and the second tray T2 is used as a desorber, the second valve V2 is open and the third valve V3 is closed. The oil and gas to be treated enter the first inlet heat exchanger E1 through the second valve V2, where it exchanges heat with the low-temperature rich absorbent formed after the oil and gas is absorbed in the first tray T1 (the absorber). After heat exchange, the oil and gas temperature is 1~2℃, and then it enters the separator G1 to separate the heavier hydrocarbon components from water, preventing these substances from frosting and clogging in the absorber. At the same time, the fifth valve V5 is open and the sixth valve V6 is closed, and the pre-cooled oil and gas enters from the bottom of the first tray T1 (the absorber); the seventh valve V7, the eighth valve V8, the tenth valve V10, the twelfth valve V12, the thirteenth valve V13, and the fifteenth valve V15 are open; the ninth valve V9, the eleventh valve V11, the fourteenth valve V14, the sixteenth valve V16, the seventeenth valve V17, and the eighteenth valve V18 are closed. The oil and gas come into countercurrent contact with the absorbent liquid that is condensed in stages in the first tray of the absorption tower T1. After being treated to meet the emission standards, the oil and gas enter the first outlet heat exchanger E4 from the top of the tower through the first mist eliminator H1, where it exchanges heat with the lean absorbent before being discharged.

[0031] The lean absorbent, after being evenly distributed by the first absorbent distributor F1, enters the first tray tower T1, which serves as the absorption tower. Inside the tower, it is condensed by the tray S1 of the first integrated refrigerant evaporation / condensation unit, absorbing dissolved oil and gas. The rich absorbent, having absorbed the oil and gas, is drawn from the bottom of the tower by the first absorbent pump P1. It first exchanges heat with the oil and gas to be treated in the first inlet heat exchanger E1, then exchanges heat with the desorbed absorbent in the lean and rich absorbent heat exchanger E2. Finally, it enters the desorption tower from the top of the second tray tower T2, which serves as the desorption tower. The rich absorbent, after being evenly distributed by the second absorbent distributor F2, enters the second tray tower T2, which serves as the desorption tower. Inside the tower, it is heated by the tray S2 of the second integrated refrigerant evaporation / condensation unit, thereby desorbing the dissolved oil and gas. At this point, the top of the second tray T2, which serves as the desorption tower, is connected to a vacuum pump P3 to maintain a certain vacuum level inside the tower, ensuring a desorption rate of ≥98%. The desorbed oil and gas are discharged from the top of the tower and then pass through the oil and gas recovery tank. The lean absorbent that has been desorbed is extracted from the bottom of the second tray T2, which serves as the desorption tower, by an absorbent pump. After exchanging heat with the lean and rich absorbent heat exchanger E2, it enters the first outlet heat exchanger E4 and exchanges heat with the external exhaust gas again. Finally, it enters the tower from the top of the second tray T2, which serves as the absorption tower, for internal circulation.

[0032] In the refrigeration cycle unit, a low-temperature, low-pressure refrigerant at -20℃ to -25℃ enters the first integrated refrigerant evaporation / condensation unit from the lower part of the first tray T1, which serves as the absorption tower. It exchanges heat with the absorbent on the tray stage by stage and vaporizes. The vaporized low-temperature, low-pressure refrigerant, at 15℃ to 20℃, exits the tower from the upper part of the first tray T1, which serves as the absorption tower. Figure 1 As shown, the gas enters the refrigeration compressor C1 through ports 4 and 3 of the four-way valve V19 and is compressed into a high-temperature, high-pressure gas at 80°C to 85°C. Subsequently, it enters the second integrated refrigerant evaporation / condensation unit's tray S2 from the upper part of the second tray T2, which serves as the desorption tower, through ports 2 and 1 of the four-way valve V19. There, it exchanges heat with the rich absorbent liquid on the tray and condenses into a medium-temperature, high-pressure refrigerant at 40°C to 45°C. This medium-temperature, high-pressure refrigerant exits the second tray T2, which serves as the absorption tower, and enters the throttling device D1 to reduce its pressure, transforming it into a low-temperature, low-pressure refrigerant. It then re-enters the first tray T1, which serves as the absorption tower, completing the entire refrigeration cycle. When the concentration, composition, and other parameters of the oil and gas to be treated change, the automatic control system can automatically optimize and adjust the amount of absorbent sprayed on the first tray T1 of the absorption tower, adjust the absorbent replenishment amount through the first valve V1, and adjust the absorbent discharge amount through the fourth valve V4; the refrigeration cycle unit can adjust the condensation temperature and desorption temperature, and the vacuum desorption unit can adjust the vacuum degree parameter, so as to realize the intelligent, energy-saving and stable operation of the device.

[0033] Taking the oil and gas recovery at a certain refined oil depot as an example, the oil and gas emission is 500m³. 3 / h, concentration of 500~600 g / m3 The requirements are: oil and gas recovery efficiency ≥ 95%, and the concentration of treated oil and gas emissions less than 25 mg / m³. 3 The system uses a special absorbent for oil and gas recovery. The refrigerant enters the absorption tower at -20℃, enters the desorption tower at 80℃, and exits the desorption tower at 45℃. With a COP of 3.0 and a waste heat recovery efficiency of 40%, the system can recover approximately 11.6 kWh of condensation heat per hour, which is equivalent to electricity, significantly reducing the energy consumption of the unit.

[0034] Example 2 differs from Example 1 in that, as Figure 1 As shown, the first tray tower T1 and the second tray tower T2 have completely identical structures. When the first tray tower T1 is used as an absorber, blockage due to condensation and frosting causes the pressure difference between the oil and gas inlet and outlet to exceed a set threshold. The device can automatically switch the function of the first tray tower T1 as an absorber and the second tray tower T2 as a desorption tower: the refrigerant switches its flow direction through the four-way valve V19 and circulates in the direction shown by the dotted arrow; the second valve V2, the fifth valve V5, the eighth valve V8, the tenth valve V10, and the thirteenth valve V13 are closed, while the third valve V3, the sixth valve V6, the ninth valve V9, the eleventh valve V11, the fourteenth valve V14, the sixteenth valve V16, and the eighteenth valve V18 are opened. At this time, the first tray tower T1, which is used as an absorber, switches to a desorption tower, and the second tray tower T2, which is used as a desorption tower, switches to an absorber.

[0035] In the initial switching phase, the oil and gas discharged from the top of the second tray T2 (acting as an absorber) and the oil and gas desorbed from the first tray T1 (acting as a desorber) are collected because the treatment effect does not meet the discharge standards. These two portions of oil and gas are then mixed with the oil and gas to be treated through valves 16 and 18 (V16 and V18) and enter the second tray T2 (acting as an absorber) for secondary treatment. Once the oil and gas discharged from the top of the second tray T2 (acting as an absorber) meets the emission standards, valves 16 and 18 (V18) are closed, and valve 17 (V17) is opened, completing the switching operation between the absorber and desorber.

[0036] After switching, the oil and gas come into counter-current contact with the progressively condensed absorbent in the second tray tower T2, which serves as the absorption tower. After being treated to meet the standards, the oil and gas enter the second outlet heat exchanger E5 from the top of the tower via the second mist eliminator H2, where it exchanges heat with the lean absorbent and is then discharged. The lean absorbent is evenly distributed by the second absorbent distributor F2 and enters the second tray tower T2, which serves as the absorption tower. Inside the tower, it is condensed by the tray S2 of the second integrated refrigerant evaporation / condensation unit and absorbs and dissolves the oil and gas. The rich absorbent, after absorbing the oil and gas, is drawn out from the bottom of the tower via the second absorbent pump P2. It first exchanges heat with the oil and gas to be treated in the second inlet heat exchanger E3, and then exchanges heat with the absorbent after desorption in the lean and rich absorbent heat exchanger E2. Finally, it enters the desorption tower from the top of the first tray tower T1, which serves as the desorption tower.

[0037] The rich absorbent is evenly distributed by the first absorbent distributor F1 and then enters the first tray tower T1, which serves as the desorption tower. Inside the tower, it is heated by the tray S1 of the first integrated refrigerant evaporation / condensation unit, desorbing the dissolved oil and gas. The top of the first tray tower T1 is connected to a vacuum pump P3 to maintain a certain vacuum level inside the tower. The desorbed oil and gas are discharged from the top of the tower and then go to the oil and gas recovery tank. The desorbed lean absorbent is extracted from the bottom of the first tray tower T1 via the first absorbent pump P1, and after exchanging heat with the lean and rich absorbent heat exchanger E2, it enters the second outlet heat exchanger E5 to exchange heat with the external exhaust gas again. Finally, it enters the second tray tower T2, which serves as the absorption tower, from the top of the tower for recycling.

[0038] The refrigeration cycle after switching is as follows: The low-temperature, low-pressure refrigerant enters the second integrated refrigerant evaporation / condensation unit's tray S2 from the lower part of the second tray T2, which serves as the absorption tower, and exchanges heat with the absorbent liquid on the tray stage by stage, thus vaporizing. The vaporized low-temperature, low-pressure refrigerant exits the tower from the upper part of the second tray T2, which serves as the absorption tower, and enters the refrigeration compressor C1 through ports 1 and 3 of the four-way valve V19, where it is compressed into a high-temperature, high-pressure gas. Subsequently, it enters the first tray T1 of the desorption tower from the upper part through ports 2 and 4 of the four-way valve V19, and exchanges heat with the rich absorbent liquid on the tray S1 of the first integrated refrigerant evaporation / condensation unit integrated in the tray layer, thus condensing into a medium-temperature, high-pressure refrigerant. This medium-temperature, high-pressure refrigerant exits the tower from the lower part of the first tray T1 of the desorption tower, enters the throttling device D1 to reduce its pressure, and then transforms into a low-temperature, low-pressure refrigerant, which re-enters the second tray T2 of the absorption tower, completing the refrigeration cycle.

[0039] Example 3 is based on Examples 1-2, but differs in that the absorption tower is a packed tower. The following describes the absorption-condensation coupled oil and gas recovery method and device proposed in this invention with specific examples and accompanying drawings.

[0040] like Figure 4 The image shows a condensation absorption coupled oil and gas recovery device using a packed tower. Figure 5 The diagram shows the structure of the first packed tower T3, which mainly consists of a first mist eliminator H1, a third absorbent distributor F3, and a packing layer S5 that integrates a refrigerant evaporation unit / condensation unit. Figure 6 The specific structure of the packing layer S5 of the third integrated refrigerant evaporation / condensation unit includes a third refrigerant inlet / outlet S301, a fourth refrigerant inlet / outlet S302, a packing layer S303, and a refrigerant flow pipeline S304. The refrigerant flow pipeline S304 is embedded inside the packing layer S303. The heat exchange area of ​​the refrigerant pipeline can be increased by means of the packing structure, thereby improving the heat exchange effect.

[0041] The packed tower adopts a multi-stage packed layer structure. The absorbent enters the packed layer S3 of the first integrated refrigerant evaporation / condensation unit and the packed layer S4 of the second integrated refrigerant evaporation / condensation unit through the third absorbent distributor F3 and the fourth absorbent distributor F4. Then, it enters the packed layer S5 of the third integrated refrigerant evaporation / condensation unit and the packed layer S6 of the fourth integrated refrigerant evaporation / condensation unit through the first absorbent re-distributor F5 and the second absorbent F6. The specific operation process of the entire device can be referred to the relevant operations in Embodiments 1 and 2.

[0042] In summary As can be seen from the results of the various embodiments of the present invention, the present invention integrates the evaporator of the refrigeration cycle unit into the tray or packing layer of the absorption tower, coupling the condensation and absorption recovery processes, giving full play to the synergistic effect of the two, and effectively improving the oil and gas recovery efficiency; at the same time, by integrating the condenser of the refrigeration cycle unit into the tray or packing layer of the desorption tower, the heat released when the high-temperature and high-pressure refrigerant is condensed after the compressor is pressurized can be recovered, which greatly reduces the overall energy consumption of the oil and gas recovery device while meeting the desorption temperature requirements of the rich absorbent.

[0043] Furthermore, the absorption tower and desorption tower can switch functions and operate alternately, effectively avoiding blockage caused by frost during the coupled operation of the absorption tower and condenser, and significantly improving the operational stability of the entire system. The absorption-condensation coupled oil and gas recovery process provided by this invention not only effectively improves oil and gas recovery efficiency and rationally utilizes the heat generated during the refrigeration cycle, but also reduces the regeneration energy consumption of the rich absorbent. The alternating operation of the absorption tower and desorption tower ensures the long-term stable operation of the system, providing a more economical and efficient technical solution for the industrial application of oil and gas recovery. It has the potential for practical production and widespread application, and is expected to generate significant social and economic benefits.

[0044] It should be noted that the term "comprising" or any other variation thereof is 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 a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0045] 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 variations 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 method for oil and gas recovery coupled with condensation absorption, characterized in that, Includes the following steps: Step 1. Pre-cooling: The oil and gas to be treated are pre-cooled by exchanging heat with the low-temperature rich absorbent after absorbing the oil and gas in the first inlet heat exchanger to remove heavier hydrocarbon components and water; Step 2. Absorption: The absorbent is condensed by the trays of the first integrated refrigerant evaporation / condensation unit and the second integrated refrigerant evaporation / condensation unit, or by the packing layers of the first integrated refrigerant evaporation / condensation unit, the second integrated refrigerant evaporation / condensation unit, the third integrated refrigerant evaporation / condensation unit, and the fourth integrated refrigerant evaporation / condensation unit. After absorbing the oil and gas, the rich absorbent exchanges heat with the oil and gas to be treated and the lean absorbent in sequence and then goes to the desorption tower. The oil and gas to be treated is discharged after condensation and absorption, meeting the standards. Step 3. Desorption: The rich absorbent is heated by the trays of the first integrated refrigerant evaporation / condensation unit and the second integrated refrigerant evaporation / condensation unit, or by the packing layers of the first integrated refrigerant evaporation / condensation unit, the second integrated refrigerant evaporation / condensation unit, the third integrated refrigerant evaporation / condensation unit, and the fourth integrated refrigerant evaporation / condensation unit, and the absorbed oil and gas are desorbed under vacuum. The desorbed lean absorbent exchanges heat with the rich absorbent and the exhaust gas outside the absorption tower in sequence and then goes to the absorption tower. The desorbed oil and gas go to the oil and gas recovery tank. Step 4. Refrigeration Cycle: Low-temperature, low-pressure refrigerant enters the refrigerant evaporation units in the lower part of the absorption tower, specifically the trays of the first and second integrated refrigerant evaporation / condensation units, or the packing layers of the first, second, third, and fourth integrated refrigerant evaporation / condensation units. After vaporizing through staged heat exchange with the absorbent, the refrigerant exits the absorption tower from the upper part and enters the refrigeration compressor unit, where it is compressed into a high-temperature, high-pressure gas and exits from the desorption tower. The refrigerant enters the trays of the first integrated refrigerant evaporation / condensation unit and the second integrated refrigerant evaporation / condensation unit, or the packing layers of the first integrated refrigerant evaporation / condensation unit, the second integrated refrigerant evaporation / condensation unit, the third integrated refrigerant evaporation / condensation unit, and the fourth integrated refrigerant evaporation / condensation unit. After being condensed into a medium-temperature and high-pressure refrigerant through heat exchange with the rich absorbent, it exits from the lower part of the desorption tower and enters the throttling device (D1) to reduce its pressure and become a low-temperature and low-pressure refrigerant. It then re-enters from the bottom of the absorption tower to complete the refrigeration cycle. Step 5. Tower switching operation: The absorption tower and desorption tower have the same structure. The refrigerant circulation direction is switched by a four-way valve (V19), so that the refrigerant evaporation unit integrated in the absorption tower is switched to the condensation unit, and the refrigerant condensation unit integrated in the desorption tower is switched to the evaporation unit, thereby realizing the switching of the operation mode of the absorption tower and the desorption tower.

2. The condensation absorption coupled oil and gas recovery method according to claim 1, characterized in that, Steps 1-5 utilize an automatic control system to automatically optimize and adjust the spray volume, replenishment and discharge volume of absorbent, condensation temperature, desorption temperature, and desorption vacuum degree in response to fluctuations in the concentration and component parameters of the oil and gas to be treated, thereby achieving intelligent and energy-saving operation.

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