Combined low-temperature oil gas recovery device

Abstract

The utility model discloses a combined low-temperature oil gas recovery device. The recovery device comprises a first-stage absorption tower in which oil gas is contacted with a first-stage absorbent to remove most of water and heavy hydrocarbon; primary absorption tail gas is in contact with a secondary absorbent in the secondary absorption tower, part of C3 and above components are condensed and absorbed, and residual water is frozen into ice particles; in the third-stage cooler, the second-stage absorption tail gas exchanges heat with a refrigerating medium, and light hydrocarbon is further removed; the filter is used for filtering the ice-containing absorption liquid, obtained ice particles enter the first-stage absorption tower, and obtained filtrate is used as a second-stage absorbent; the primary circulating pump is used for circularly spraying the primary absorbent; and the second-stage circulating pump is used for circulating the second-stage absorption liquid to the filter so as to realize circulating spraying of the second-stage absorbent after deicing. The oil gas recovery device has the advantages of being stable and reliable in process, simple in equipment, safe, energy-saving and the like.

Description

Technical Field

[0001] This utility model belongs to the field of environmental protection and energy conservation technology, and relates to an oil and gas recovery and treatment method and device, specifically an oil and gas recovery and treatment method and device for tank farms. Background Technology

[0002] During the storage and cleaning processes of oil products in tank farms, a significant amount of oil vapors and volatile organic compounds (VOCs) are released. Statistics show that approximately 0.5% of light oil products are lost annually due to these releases. This results in a substantial waste of oil vapors and VOCs, reducing the economic benefits for enterprises, and also causes serious environmental pollution. Furthermore, because oil vapors and air easily form explosive mixtures (with a lower explosive limit generally between 1% and 6%), the release of oil vapors can cause the concentration of oil vapors around the affected facilities to easily reach explosive limits. Oil vapors accumulating on the ground pose a significant safety hazard to enterprises and consumers, endangering safe production and directly impacting the health of operators and those in the surrounding environment. Therefore, the recovery and treatment of released oil vapors is essential.

[0003] There are three traditional methods for oil and gas recovery and treatment: one is to use it directly as fuel; the second is to return the oil and gas to the oil tank gas-liquid balance system to increase the partial pressure of oil and gas and reduce the loss of oil evaporation; the third is to use recovery devices and technologies, such as condensation, absorption, adsorption and their combination processes.

[0004] Patent CN202246576 U discloses a cryogenic condensation absorption and recovery device for oil and gas, including a refrigeration unit, a lean absorbent delivery pump, a venturi ejector, an oil and gas condensation absorption mixture separator, an oil and gas precooler heat exchanger, and a precooler oil and gas gas-liquid separator. Oil and gas are introduced into the venturi ejector and mixed with the cryogenic absorbent, and the oil and gas components are separated by the cryogenic absorbent through condensation and cooling. However, at the same time, the moisture in the oil and gas will be condensed and frozen by the sub-zero absorbent, and the device has an ice blockage problem during operation.

[0005] Patent CN204637927 U discloses an oil and gas recovery device. The oil and gas are first dried, then absorbed by gasoline at -30°C, with the exhaust gas used as regeneration gas for the dryer. During operation, the molecular sieve inside the dryer simultaneously adsorbs oil and gas components. During microwave thermal desorption, these components enter the regeneration gas, increasing the concentration of oil and gas in the exhaust gas and posing a safety risk of overheating the adsorbent bed.

[0006] CN101342427A discloses a method for recovering oil and gas using a combined condensation-adsorption process. The oil and gas first undergo cooling-condensation to separate some of their components. Uncondensed oil and gas are recovered by adsorption-pressure swing desorption. The adsorption tail gas meets emission standards, and the desorbed oil and gas is returned to the cooling device to mix with the collected oil and gas before entering the condenser. The recommended oil and gas condensation temperature is -80℃ to 30℃, preferably -70℃ to 40℃. This method primarily relies on condensation and liquefaction to recover oil and gas components. However, the low condensation temperature leads to crystallization within the condenser, requiring periodic removal of water crystals and condensed oil. Therefore, two series of condensers need to be used interchangeably. The overall energy consumption of the device is relatively high, and the failure rate of the refrigeration equipment is also relatively high. Furthermore, crystallization also occurs in the subsequent adsorption tank, significantly reducing the lifespan of the adsorbent.

[0007] At present, the condensation method is mainly used to recover oil and gas in the exhaust of oil loading vehicles. The condensation temperature is -35℃ to -75℃. However, the condensation method oil and gas treatment device has the following problems during operation: (1) The condensation system is severely frosted. There is ice blockage at the switching valve or pipeline of condensation and defrosting, which makes it difficult for the condensation system to operate stably; (2) The defrosting process uses hot gas defrosting, such as hot nitrogen or refrigerant hot vapor. Using hot nitrogen defrosting increases the refrigeration load of the condensing unit, thereby increasing the condensing energy consumption; using refrigerant hot vapor defrosting not only causes the refrigeration system to operate stably and increases the configuration of the refrigeration system, but also increases the unit's operating power. Utility Model Content

[0008] To address the shortcomings of existing condensation-based oil and gas recovery devices, this invention provides a combined cryogenic oil and gas recovery device. This device eliminates the problem of system ice blockage and offers advantages such as stable and reliable operation, simple equipment, safety, and energy efficiency.

[0009] The combined cryogenic oil and gas recovery device provided by this utility model includes:

[0010] In the primary absorption tower, the oil and gas cooled by the oil and gas cooler and the oil and gas heat exchanger come into contact with the primary absorbent. At the top of the tower, the primary absorption tail gas is obtained, and at the bottom of the tower, the primary absorbent liquid (agent) containing water and heavy hydrocarbons is obtained.

[0011] In a two-stage absorption tower, the tail gas from the first-stage absorption is contacted with the secondary absorbent from the secondary cooler to obtain the tail gas from the second-stage absorption and the ice-containing secondary absorbent.

[0012] The three-stage cooler further cools the exhaust gas after the second-stage absorption, resulting in purified gas and condensed oil.

[0013] The filter is used to filter the ice-containing secondary absorbent obtained from the secondary absorption tower to obtain ice particles and filtrate; the obtained ice particles are then transported to the lower part of the primary absorption tower, and the obtained filtrate is transported to the inlet of the secondary cooler.

[0014] The primary circulation pump is used to circulate the primary absorbent liquid in the lower storage section of the primary absorption tower through the primary cooler to the primary absorbent inlet at the upper part of the primary absorption tower.

[0015] The secondary circulation pump is used to circulate the secondary absorbent obtained from the secondary absorption tower to the filter, and to deliver the filtrate obtained from the filter to the secondary cooler.

[0016] Furthermore, the primary absorption tower has a cylindrical structure, comprising an upper absorption section and a lower storage section. The lower end of the absorption section has a primary oil / gas inlet, the upper end has a primary absorbent inlet, and the interior of the upper end of the section is equipped with an absorbent spray system. The top end of the absorption section has a primary absorption tail gas exhaust port. The middle of the storage section has a primary absorbent liquid outlet, the upper end has an ice particle inlet, and the bottom end of the storage section has a drain outlet.

[0017] Furthermore, the secondary absorption tower has a cylindrical structure. The lower end of the absorption section is provided with a secondary oil and gas (i.e., primary absorption tail gas) inlet, the upper end of the cylinder is provided with a secondary absorbent inlet, the upper part of the cylinder is provided with an absorbent spraying facility, the top end of the absorption section is provided with a secondary absorption tail gas exhaust port, and the bottom end is provided with a secondary absorption liquid outlet.

[0018] Furthermore, the three-stage cooler cylinder is a cylindrical structure, comprising an upper condensation section and a lower liquid storage section. The upper end of the condensation section cylinder is provided with a three-stage oil-gas (i.e., a two-stage absorption tail gas) inlet and a cooling medium inlet, the lower end of the condensation section cylinder is provided with a purified gas outlet and a cooling medium outlet, and the bottom end cap of the liquid storage section is provided with an oil drain port.

[0019] Furthermore, the lower cylinder of the spray system within the primary absorption tower is equipped with packing material for absorbent distribution, enhancing gas-liquid mass and heat transfer. The spray system within the primary absorption tower is connected to its primary absorbent inlet, enabling the absorbent to be sprayed and dispersed within the tower.

[0020] Furthermore, the lower part of the spraying facility in the secondary absorption tower is an empty tower, and the spraying facility in the secondary absorption tower is connected to the inlet of its secondary absorbent, so as to achieve spraying and dispersion of the absorbent in the tower.

[0021] Furthermore, the three-stage cooler is preferably a shell-and-tube heat exchanger with gas-liquid separation, with oil and gas flowing through the tubes and the low-temperature cooling medium flowing through the shell.

[0022] Furthermore, the top of the primary and secondary absorption towers is preferably equipped with a demisting section, which is used to capture the mist droplets carried in the exhaust gas of the primary and secondary absorption towers, respectively.

[0023] Furthermore, the combined cryogenic oil and gas recovery device of this utility model includes an induced draft fan, which is used to introduce oil and gas into the oil and gas recovery device. The inlet of the induced draft fan is connected to the oil and gas inlet pipe, and the outlet of the induced draft fan is connected to the inlet of the oil and gas cooler.

[0024] Furthermore, the outlet of the oil-gas cooler is connected to the high-temperature oil-gas inlet of the oil-gas heat exchanger, and the high-temperature oil-gas outlet of the oil-gas heat exchanger is connected to the oil-gas inlet of the absorption section of the primary absorption tower.

[0025] Furthermore, the exhaust port of the primary absorption tower is connected to the oil and gas inlet of the secondary absorption tower via a pipeline; the absorbent outlet of the primary absorption tower is connected to the inlet of the primary circulating pump, the outlet of the primary circulating pump is connected to the inlet of the primary cooler, and the outlet of the primary cooler is connected to the inlet of the primary absorbent; the drain outlet at the bottom of the primary absorption tower is connected to the drainage pipeline.

[0026] Furthermore, the oil and gas inlet of the secondary absorption tower is connected to the exhaust port of the primary absorption tower via a pipeline; the exhaust port of the secondary absorption tower is connected to the oil and gas inlet of the tertiary cooler via a pipeline; the absorbent outlet of the secondary absorption tower is connected to the inlet of the secondary circulation pump; the outlet of the secondary circulation pump is connected to the inlet of the filter; the slag discharge port at the bottom of the filter is connected to the ice particle inlet of the primary absorption tower; the liquid outlet of the filter is connected to the inlet of the secondary cooler; and the outlet of the secondary cooler is connected to the inlet of the secondary absorbent.

[0027] Furthermore, the oil and gas inlet of the tertiary cooler is connected to the exhaust port of the secondary absorption tower through a pipeline; the exhaust port of the tertiary cooler is connected to the low-temperature oil and gas inlet of the oil and gas heat exchanger through a pipeline, and the low-temperature oil and gas outlet of the oil and gas heat exchanger is connected to the purified gas pipeline; the refrigerant inlet and refrigerant outlet of the tertiary cooler are connected to the outlet and inlet of the refrigeration unit, respectively; and an oil drain port is provided at the bottom of the tertiary cooler, which is connected to the oil drain pipeline.

[0028] Oil-gas coolers and oil-gas heat exchangers can adopt conventional heat exchanger structures in this field. The tertiary cooler uses a partitioned heat exchanger with gas-liquid separation.

[0029] Furthermore, the inlet of the primary circulation pump is equipped with a primary replenishment pipe, and the inlet of the secondary circulation pump is equipped with a secondary replenishment pipe.

[0030] Furthermore, a centrifugal pump is preferred for the primary circulation pump, and a slurry pump is preferred for the secondary circulation pump.

[0031] Other technologies in this utility model's combined cryogenic oil and gas recovery device, such as refrigeration technology, heat exchange technology, and gas-liquid separation technology, are well-known to those skilled in the art.

[0032] The combined cryogenic oil and gas recovery device of this utility model is suitable for the recovery and treatment of oil and gas, especially for the recovery and treatment of oil and gas in storage tank areas.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. In this utility model of combined low-temperature oil and gas recovery device, the first-stage absorption tower is used to cool and separate most of the water and heavy components in the oil and gas; the second-stage absorption tower is used to separate some of the C3-C5 components and the remaining water in the oil and gas; and the third-stage cooler is used to separate the remaining C3-C5 components in the oil and gas. The oil and gas recovery efficiency is high and the effect is good. The first-stage absorption tower can prevent heavy components in the oil and gas from entering the absorbent in the second-stage absorption tower, thereby increasing the cold filter point of the absorbent in the second-stage absorption tower and extending the long-term cycle use of the absorbent. The second-stage absorption tower can prevent water from entering the third-stage cooler, thereby preventing frost or ice blockage in the third-stage cooler.

[0035] 2. Through the combined low-temperature oil and gas recovery device of this utility model, the oil and gas to be treated can be completely dehydrated by primary absorption, secondary absorption and tertiary absorption; by separating oil and water and filtering water into ice particles, the water in the oil and gas is discharged from the oil and gas recovery device, which can effectively avoid the problem of ice blockage in the current condensation method oil and gas recovery device system. At the same time, this utility model does not require the defrosting process of heat exchanger, which simplifies the process flow and greatly saves system energy consumption.

[0036] 3. In the combined low-temperature oil and gas recovery device of this utility model, the oil and gas heat exchanger is used to exchange heat between the exhaust gas of the three-stage cooler and the pressurized and cooled oil and gas, which effectively utilizes the cold energy contained in the low-temperature absorption exhaust gas and saves energy consumption.

[0037] 4. The combined low-temperature oil and gas recovery device of this utility model has the advantages of stable and reliable process, simple equipment, safety and energy saving. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the combined low-temperature oil and gas recovery device of this utility model.

[0039] Among them, 101-exhaust fan, 102-oil-gas cooler, 103-oil-gas heat exchanger, 104-primary absorption tower, 104A-absorption section of primary absorption tower, 104B-liquid storage section of primary absorption tower, 105-primary circulating pump, 106-primary cooler, 107-secondary absorption tower, 108-tertiary cooler, 109-secondary circulating pump, 110-filter, 111-secondary cooler;

[0040] 1- Primary oil and gas inlet, 2- Primary absorbent inlet, 3- Primary absorption tail gas exhaust port, 4- Primary absorbent liquid outlet, 5- Ice particle inlet, 6- Drain outlet, 7- Secondary oil and gas inlet, 8- Secondary absorbent inlet, 9- Secondary absorption tail gas exhaust port, 10- Secondary absorbent liquid outlet, 11- Cooling medium outlet, 12- Cooling medium inlet, 13- Tertiary oil and gas inlet, 14- Purified gas outlet, 15- Oil outlet, 16- Liquid inlet, 17- Absorbent outlet, 18- Slag outlet. Detailed Implementation

[0041] The present invention will be further illustrated by specific embodiments below, but is not limited to the embodiments described below.

[0042] Combination Figure 1 The combined low-temperature oil and gas recovery device of this utility model includes: an exhaust fan 101, an oil and gas cooler 102, an oil and gas heat exchanger 103, a primary absorption tower 104, a secondary absorption tower 107, a tertiary cooler 108, a primary circulation pump 105, a secondary circulation pump 109, a primary cooler 106, a secondary cooler 111, a filter 110, and related connecting pipes.

[0043] The primary absorption tower 104 contains oil and gas that have been cooled by heat exchanger 102 and oil and gas cooler 103, which come into contact with primary absorbent from primary cooler 106. Primary absorption tail gas is obtained at the top of the tower, and primary absorption liquid containing water and heavy hydrocarbons is obtained at the bottom of the tower.

[0044] In the secondary absorption tower 107, the primary absorption tail gas comes into contact with the secondary absorbent from the secondary cooler 111, and the secondary absorption tail gas is obtained at the top of the tower, while the secondary absorbent containing ice particles is obtained at the bottom of the tower.

[0045] The three-stage cooler 108 uses a low-temperature cooling medium to further cool the exhaust gas from the second-stage absorption stage, resulting in purified gas and condensed oil.

[0046] The filter 110 filters the ice-containing secondary absorption liquid obtained from the secondary absorption tower 107 to obtain ice particles and filtrate; and the obtained ice particles are transported to the lower liquid storage section 104B of the primary absorption tower 104, and the obtained filtrate is transported to the inlet of the secondary cooler 111.

[0047] The primary circulation pump 105 is used to circulate the primary absorbent in the lower storage section of the primary absorption tower to the inlet of the primary cooler 106, and then to the inlet of the primary absorbent in the upper part of the primary absorption tower.

[0048] The secondary circulation pump 109 is used to transport the ice-containing absorbent obtained from the secondary absorption tower 107 to the filter 110, and to transport the secondary absorbent (agent) obtained from the filter 110 to the secondary cooler 111.

[0049] The primary absorption tower 104 has a cylindrical structure, comprising an upper absorption section 104A and a lower liquid storage section 104B. The lower end of the absorption section 104A has a primary oil / gas inlet 1, the upper end has a primary absorbent inlet 2, the upper part of the cylinder has an absorbent spray system, and the top end cap of the absorption section has a primary absorption tail gas exhaust port 3. The middle of the liquid storage section 104B has a primary absorbent liquid outlet 4, the upper part of the liquid storage section has an ice particle inlet 5, and the bottom end cap of the liquid storage section has a drain outlet 6.

[0050] Furthermore, the primary absorption tower 104 can be a packed tower or a plate tower, with a packed tower being preferred.

[0051] The secondary absorption tower 107 also has a cylindrical structure. The lower end of the cylinder is equipped with a secondary oil and gas (i.e., primary absorption tail gas) inlet 7, the upper end of the cylinder is equipped with a secondary absorbent inlet 8, the upper end of the cylinder is equipped with an absorbent spraying facility, the top end of the absorption section is equipped with a secondary absorption tail gas exhaust port 9 for discharging the secondary absorption tail gas, and the bottom end is equipped with a secondary absorption liquid outlet 10 for discharging the secondary absorption liquid.

[0052] Furthermore, the secondary absorption tower 107 can be a bubble tower or a spray tower, with a spray tower being preferred.

[0053] The three-stage cooler 108 has a vertical cylindrical structure, including an upper condensation section 108A and a lower liquid storage section 108B. The upper end of the condensation section 108A is provided with a three-stage oil and gas (i.e., a two-stage absorption tail gas) inlet 13 and a cooling medium inlet 12. The lower end of the condensation section 108A is provided with a purified gas outlet 14 and a cooling medium outlet 11. The bottom end cap of the liquid storage section is provided with an oil drain port 15.

[0054] The lower cylinder of the spray system inside the primary absorption tower 104 is filled with packing material for absorbent distribution, enhancing gas-liquid mass and heat transfer. The spray system inside the primary absorption tower is connected to the inlet of its primary absorbent, enabling the absorbent to be sprayed and dispersed within the tower.

[0055] A spray system is installed in the upper part of the secondary absorption tower 107, with an empty tower below the spray system. The spray system in the secondary absorption tower is connected to the inlet of its secondary absorbent to achieve spray dispersion of the absorbent within the tower.

[0056] The three-stage cooler 108 is preferably a shell-and-tube heat exchanger with gas-liquid separation, preferably with oil and gas flowing through the tubes and the low-temperature cooling medium flowing through the shell.

[0057] The top of the primary absorption tower 104 and the secondary absorption tower 107 are preferably provided with a demisting section, which is used to capture the mist droplets carried in the tail gas of the primary absorption tower and the tail gas of the secondary absorption tower, respectively.

[0058] The filter 110 includes a liquid inlet 16, an absorbent outlet 17 for discharging secondary absorbent, and a slag outlet 18 for discharging ice particles.

[0059] Combination Figure 1 The working process of the combined low-temperature oil and gas recovery device provided by this utility model is as follows:

[0060] (1) The oil and gas to be processed is Stream I. Stream I is pressurized by the exhaust fan 101, cooled by the oil and gas cooler 102, and heated by the oil and gas heat exchanger 103. The resulting oil and gas is Stream II. Stream II enters the first-stage absorption tower 104.

[0061] (3) The oil and gas (material II) entering the first-stage absorption tower undergoes countercurrent mass transfer and heat transfer with the absorbent at 4~8℃ in the first-stage absorption tower. Most of the C6 and above components are absorbed and condensed into the absorbent. At the same time, the water in material II is cooled and separated. Most of the cooled water also enters the absorbent. The exhaust gas at the top of the first-stage absorption tower is the tail gas of the first-stage absorption tower (material III), which is sent to the second-stage absorption tower 107. The absorbent used in the first-stage absorption process is pressurized and circulated by the first-stage circulation pump 105. Before entering the first-stage absorption tower 104, the absorbent is cooled to 4~8℃ by the first-stage cooler 106.

[0062] (4) The tail gas of the first-stage absorption tower (material III) enters the second-stage absorption tower 107 for absorption and treatment. Material III is in the second-stage absorption tower and undergoes countercurrent mass transfer and heat transfer with the absorbent at -30~-40℃. Most of the C3 and above components are absorbed and condensed into the absorbent. At the same time, the water in material III is condensed into ice. The water in material III comes into contact with the sub-zero absorbent and is directly condensed into ice particles. The exhaust gas at the top of the second-stage absorption tower is the tail gas of the second-stage absorption tower (material IV). The absorbent used in the second-stage absorption process is pressurized and circulated by the second-stage circulation pump 109. The ice particles in the absorbent are filtered and separated in the filter 110. The ice particles are sent to the first-stage absorption tower 104 through the pipeline. The filtrate enters the second-stage cooler 111 and is cooled to -30~-40℃ before re-entering the second-stage absorption tower to absorb and treat the oil and gas.

[0063] (5) The tail gas of the secondary absorption tower (material IV) enters the tertiary cooler 108 for heat exchange treatment. Material IV undergoes indirect heat exchange with the low temperature cooling medium of -65~-70℃ in the tertiary cooler. The remaining C3 and above components condense and fall into the liquid storage section at the bottom of the tertiary cooler. The exhaust gas of the tertiary cooler is the tail gas of the tertiary cooler (material V).

[0064] (6) The tail gas (material V) obtained from the three-stage cooler 108 and the pressurized and cooled oil and gas exchange heat through the oil and gas heat exchanger 103 to obtain purified gas with a temperature of 40~45℃; the purified gas can be further treated in boilers, catalytic oxidation, regenerative oxidation and adsorption devices to meet emission standards.

[0065] Among them, the oil-gas cooler 102 and the oil-gas heat exchanger 103 adopt conventional heat exchanger structures in this field. The tertiary cooler 108 adopts a partitioned heat exchanger with gas-liquid separation, and the temperature of the inlet low-temperature cooling medium is -65~-70℃.

[0066] The primary absorption tower 104 operates at a pressure of 0~200 kPa and an absorption temperature of 4~8℃. The secondary absorption tower 107 operates at a pressure of 0~200 kPa and an absorption temperature of -30~-40℃.

[0067] The absorbent used in the primary and secondary absorption towers can be oil products with a distillation range of 30~200℃, and the absorbent is recycled. The low-temperature cooling medium of the tertiary cooler is the refrigerant of the refrigeration unit.

[0068] The exhaust fan pressurizes the oil and gas to be treated (Purpose I) to about 20 kPa. The pressurized oil and gas is cooled to 50~60℃ by the oil and gas cooler, and then heats it through the oil and gas heat exchanger to obtain oil and gas at 35~40℃ (Purpose II).

[0069] The refrigeration technology, heat exchange technology, and gas-liquid separation technology involved are all familiar to professionals in this field.

[0070] This utility model of a combined cryogenic oil and gas recovery device uses a primary absorption tower to cool and separate most of the water and heavy components in the oil and gas, a secondary absorption tower to separate some of the C3-C5 components and the remaining water, and a tertiary cooler to separate the remaining C3-C5 components. It has high oil and gas recovery efficiency and good effect, effectively avoiding the ice blockage problem of current condensation-based oil and gas recovery systems, and can also extend the long-term cycle of absorbent use. It has the advantages of stable and reliable process, simple equipment, safety and energy saving.

Claims

1. A combined cryogenic oil and gas recovery unit, characterized in that, The low-temperature oil gas recovery device comprises: a first absorption tower, in which oil gas cooled by an oil gas cooler and an oil gas heat exchanger is contacted with a first absorbent, and first absorption tail gas is obtained at the top of the tower, and first absorption liquid containing water and heavy hydrocarbon is obtained at the bottom of the tower; a second absorption tower, in which the first absorption tail gas is contacted with a second absorbent from a second cooler, and second absorption tail gas and second absorption liquid containing ice are obtained; a third cooler, in which the second absorption tail gas is further cooled to obtain purified gas and condensed oil; a filter, in which the second absorption liquid containing ice obtained from the second absorption tower is filtered to obtain ice particles and filtrate, and the ice particles are transported to the lower part of the first absorption tower, and the filtrate is transported to the inlet of the second cooler; a first circulating pump, which is used to circulate the first absorption liquid in the lower storage section of the first absorption tower to the absorbent inlet of the upper part of the first absorption tower after being cooled by a first cooler; a second circulating pump, which is used to circulate the second absorption liquid obtained from the second absorption tower to the filter, and transport the filtrate obtained from the filter to the second cooler; the third cooler is a shell-and-tube heat exchanger with gas-liquid separation, in which oil gas passes through the tube side, and low-temperature cooling medium passes through the shell side; and the cylinder body of the third cooler is a vertical cylindrical structure.

2. The combined cryogenic oil and gas recovery unit of claim 1, wherein, The cylinder body of the first absorption tower comprises an upper absorption section and a lower storage section; the middle part of the cylinder body of the storage section is provided with an absorption liquid outlet, the upper part of the cylinder body is provided with an ice particle inlet, and the bottom head of the storage section is provided with a drain port.

3. The combined cryogenic oil and gas recovery unit of claim 2, wherein, The lower end of the cylinder body of the absorption section of the first absorption tower is provided with an oil gas inlet, the upper end of the cylinder body is provided with an absorbent inlet, the upper part of the cylinder body is provided with absorbent spraying facilities, and the top head of the absorption section is provided with a gas outlet.

4. The combined cryogenic oil and gas recovery unit of claim 1, wherein, The lower end of the cylinder body of the second absorption tower is provided with an oil gas inlet, the upper end of the cylinder body is provided with an absorbent inlet, the upper part of the cylinder body is provided with absorbent spraying facilities, the top head of the absorption section is provided with a gas outlet, and the bottom head is provided with an absorption liquid outlet.

5. The combined cryogenic oil and gas recovery unit of claim 1, wherein, The third cooler comprises an upper condensation section and a lower storage section, the upper end of the cylinder body of the condensation section is provided with an oil gas inlet and a cooling medium inlet, the lower end of the cylinder body of the condensation section is provided with an oil gas outlet and a cooling medium outlet, and the bottom head of the storage section is provided with an oil outlet.

6. The modular cryogenic oil and gas recovery unit of claim 1, wherein, The lower part of the cylinder body of the first absorption tower is provided with a filler; and / or The lower part of the spraying facilities in the second absorption tower is an empty tower.

7. The combined cryogenic oil and gas recovery unit of claim 1, wherein, A demisting section is arranged at the top of the first absorption tower, and / or A demisting section is arranged at the top of the second absorption tower.

8. The modular cryogenic oil and gas recovery unit of claim 1, wherein, The low-temperature oil gas recovery device further comprises an air induction fan for inducing oil gas into the oil gas recovery device.

9. The modular cryogenic oil and gas recovery unit of claim 1, wherein, The inlet of the first circulating pump is provided with a first liquid supplementing pipe, and / or The inlet of the second circulating pump is provided with a second liquid supplementing pipe.

10. The combined cryogenic oil and gas recovery unit of claim 1, wherein, The first circulating pump is a centrifugal pump, and / or The second circulating pump is a slurry pump.

Images