Absorption and desorption and liquid nitrogen cryogenic system for oil gas recovery treatment

Abstract

The utility model relates to an adsorption and desorption and liquid nitrogen cryogenic system for oil gas recovery treatment, which comprises a shallow cooling unit, an adsorption and desorption unit and a liquid nitrogen cryogenic recovery unit, the shallow cooling unit is used for primarily cooling oil gas to separate a gas phase and a liquid phase, and the separated gas phase enters the adsorption and desorption unit through a fan to remove VOCs (Volatile Organic Compounds); and then the residual gas enters the liquid nitrogen cryogenic recovery unit through an extraction pump to obtain a residual liquid phase. Liquid nitrogen is used for deep cooling, so that energy consumption of the device is greatly reduced, the using amount of the liquid nitrogen can be adjusted according to the actual temperature requirement, nitrogen obtained after the liquid nitrogen is gasified is not polluted and has certain pressure, and the nitrogen passes through the nitrogen storage tank, then is adjusted to be slightly higher than the pressure of the nitrogen pipe network through the valve group and enters the nitrogen pipe network of the tank field to be recycled; the device is used for nitrogen sealing and purging of a storage tank, nitrogen purging and vacuum breaking of an adsorption and desorption unit of the system and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of petroleum processing, in particular to an adsorption and desorption and liquid nitrogen deep cooling system for oil and gas recovery and processing. Background Art

[0002] During the production, development, loading, unloading, transportation, storage and processing of oil, a large amount of volatile organic compounds (VOCs) will be generated. The main components are the volatile gases of crude oil and refined oil (gasoline, naphtha, aviation kerosene, solvent oil, etc.), plus a mixture of air and inert gases, collectively referred to as oil and gas. Currently, the commonly used oil and gas recovery methods are mainly absorption, adsorption, condensation and membrane separation.

[0003] The absorption method is to select a specific absorbent to dissolve and absorb the hydrocarbon components in the oil and gas so that the exhaust gas can meet the specified standards. This method has a simple process flow, low investment and operating costs, and a long service life, but the oil and gas recovery effect is not good, and the relevant indicators in the exhaust gas cannot meet the emission limits. If you want to achieve a better oil and gas recovery effect, you can consider adding an absorption tower if there is sufficient space, but if the space is tight, you need to invest a lot of absorbent, which will greatly increase the energy consumption of the refrigeration unit. No matter which improvement method is chosen, it will greatly increase investment and operating costs.

[0004] The adsorption method uses a specific adsorbent (currently the most commonly used adsorbent is activated carbon) to selectively adsorb the hydrocarbon components in the oil and gas so that the exhaust gas can meet the specified standards. At the same time, the activated carbon after adsorption saturation is vacuum desorbed to desorb the hydrocarbon components attached to the activated carbon for subsequent treatment. If it is a small air volume and low concentration of waste gas, a single-stage adsorption process can be used; if it is a large air volume or high concentration of waste gas, the use of a single machine adsorption cannot make the exhaust gas meet the emission standards. Therefore, for this kind of waste gas, especially the high concentration of oil and gas emitted during the loading and unloading and storage stages, a two-stage or multi-stage adsorption system is required to ensure that the exhaust gas can be continuously and stably discharged in compliance with the standards. However, the consequence of such treatment is that the equipment will occupy a large area and have high investment and operating costs.

[0005] The condensation method uses the changing relationship between temperature and vapor pressure of hydrocarbon components to continuously cool the oil and gas, so that most of the hydrocarbon components are condensed into liquid, thereby achieving the purpose of oil and gas recovery. However, it is difficult to achieve standard exhaust emissions using only this method. If a better treatment effect is to be achieved, a large amount of condensation equipment and refrigerants are required, which not only occupies a large area, is difficult to maintain, and consumes a lot of energy, but also results in high investment and operating costs.

[0006] Membrane separation is the separation of different components in oil and gas based on the selective permeability of specific membrane materials. This method generally has a low tail gas emission concentration, simple process, and small footprint, but the membrane components have a short life and need to be replaced frequently. In addition, since the commonly used membrane materials are mainly imported, the investment and operating costs are high.

[0007] For oil and gas in the loading and unloading and storage stages, especially at port terminals and stations, due to limited space and strict requirements on the discharge of solid waste and wastewater generated by exhaust gas treatment, it is urgent to develop a new process that can flexibly adapt to site restrictions, occupy a small area, has relatively low investment and operating costs, generates no wastewater, has high oil and gas recovery efficiency, and has a high utilization rate of recovered oil products, and can simultaneously achieve efficient pollution reduction and carbon reduction.

[0008] Defects and shortcomings of the existing technology:

[0009] Existing technologies include single processes and increasingly widely used combined processes. For example:

[0010] 1. CN116549996A mentions an energy-saving VOCs oil and gas recovery and treatment system and recovery method. The recovery method first performs shallow cooling on the oil and gas, then performs deep cooling with liquid nitrogen, and finally enters the catalytic oxidation system. This method has high liquid nitrogen consumption, incomplete cold recovery, and the catalytic oxidation system consumes a lot of energy and has high carbon emissions, which will not be able to meet the carbon emission indicators in national standards in the future.

[0011] 2. CN219355811U mentions a low-energy consumption treatment device for waste gas containing volatile organic compounds. The treatment equipment includes a shallow cooler, liquid nitrogen deep cooling and an incinerator. This method consumes a large amount of liquid nitrogen, which will cause a large amount of nitrogen waste and cold waste. The incineration device will also produce a large amount of carbon emissions and high energy consumption. It will not be able to meet the carbon emission indicators in the national standards in the future.

[0012] 3. CN113318557B mentions an oil and gas recovery and treatment system and an oil and gas recovery and treatment method. The equipment includes: a deep cooling system, an adsorption system and a biocatalytic oxidation system. This system will also cause a large amount of nitrogen and cold capacity waste, and the use of this method alone cannot meet the increasingly stringent exhaust emission requirements in national standards.

[0013] 4. CN110385012A mentions a cryogenic oil and gas recovery device, including an exhaust gas buffer tank, a first liquid nitrogen cryogenic device and a second liquid nitrogen cryogenic device. This device will cause a large amount of nitrogen and cooling capacity to be wasted, and a single liquid nitrogen cryogenic device cannot meet the increasingly stringent national requirements.

[0014] In summary, these methods in the prior art have various limitations for the oil and gas processing field, especially for the oil and gas loading and unloading and storage stages at ports, terminals and stations, mainly including: site restrictions, large land area, relatively high investment and operation costs, waste of resources and energy, low oil and gas recovery efficiency, low utilization of recovered oil products, substandard tail gas emissions, and failure to simultaneously achieve efficient pollution reduction and carbon reduction, etc. Therefore, it is urgent to research and develop new processes that can solve or avoid the above problems. Utility Model Content

[0015] The purpose of the utility model is to overcome the deficiencies of the prior art, especially for oil and gas recovery and treatment in the loading and unloading and storage stages of ports, terminals and stations, and to provide an adsorption, desorption and liquid nitrogen cryogenic system, which utilizes an adsorber and a liquid nitrogen cryogenic system to recover and treat the oil and gas. The process is simple and less susceptible to site restrictions, ensuring that no wastewater is generated after treatment, high oil and gas recovery efficiency, high utilization rate of recovered oil products, up-to-standard exhaust emissions, and efficient pollution reduction and carbon reduction can be achieved at the same time.

[0016] In order to achieve the above utility model purpose, the technical solution adopted is as follows:

[0017] The oil and gas recovery process of the utility model is as follows:

[0018] 1. An adsorption-desorption and liquid nitrogen cryogenic system for oil and gas recovery and treatment, characterized by: a shallow cooling unit, an adsorption-desorption unit and a liquid nitrogen cryogenic recovery unit. The shallow cooling unit initially cools the oil and gas to separate the gas phase and the liquid phase. After separation, the gas phase enters the adsorption-desorption unit through a fan to remove VOCs, and then the residual gas enters the liquid nitrogen cryogenic recovery unit through a production pump to remove the residual liquid phase;

[0019] The shallow cooling unit comprises a flame arrester (X101), a shallow cooler (E101), a gas-liquid separator (V101), a fan (C101) and related connecting pipelines; the oil and gas outlet of the flame arrester is connected to the oil and gas inlet of the shallow cooler, the oil and gas inlet of the shallow cooler is connected to the inlet of the gas-liquid separator, the gas outlet at the top of the gas-liquid separator is connected to the inlet of the fan (C101) of the adsorption and desorption unit; the liquid outlet at the bottom of the gas-liquid separator is connected to the storage tank through a production pump; the cold source circulation pipe of the shallow cooler (E101) is connected to the nitrogen pipeline network;

[0020] The adsorption-desorption unit comprises two parallel adsorbers (V102A, V102B), the inlet of the adsorber is connected to the residual gas after shallow cooling through a fan, the top outlets of the two parallel adsorbers are respectively connected in parallel to the nitrogen inlet pipe and the discharge outlet pipe, and the adsorbers are filled with adsorbent; the two bottom outlets of the adsorption-desorption unit are connected to the liquid nitrogen deep-cold recovery unit after passing through a vacuum pump;

[0021] The liquid nitrogen cryogenic recovery unit comprises three-stage condensers (E102A, E102B, E102C) with the same structure, three-stage gas-liquid separators (V103A, V103B, V103C) with the same structure and a liquid nitrogen tank (V104), the three-stage condensers and the three-stage gas-liquid separators are arranged at intervals, the gas phase outlet of each stage condenser is connected to the middle gas phase inlet of the adjacent first-stage gas-liquid separator, the top gas phase outlets of the first-stage and second-stage gas-liquid separators are respectively connected to the middle gas phase inlet of the next-stage gas-liquid separator, the gas phase outlet of the third-stage gas-liquid separator is connected to the middle air inlet of the gas-liquid separator, the lower liquid phase outlets of the three-stage gas-liquid separators are all connected to a liquid storage tank (V105), and the cold source circulation pipe of the condenser is connected to the outlet of the liquid nitrogen tank, so as to provide cold source circulation for adjacent gas-liquid separators respectively.

[0022] Moreover, the cold source outlet of the tertiary condenser is connected to the shallow cooler inlet.

[0023] Furthermore, the liquid nitrogen tank is connected to the three-stage condenser via a liquid nitrogen pump (P104).

[0024] Moreover, the gas overflow port at the top of the liquid storage tank (V105) is connected to the middle gas inlet of the gas-liquid separator.

[0025] The utility model has the following beneficial effects:

[0026] 1. This application combines the advantages of the adsorption method and the condensation method, and the process is simple, the floor space is reduced, and the site restrictions are small. The frequency of adsorbent replacement is greatly reduced, reducing operating costs. After system treatment, no wastewater is generated, tail gas emissions meet standards, and efficient pollution reduction and carbon reduction can be achieved at the same time. Not only does it effectively utilize the advantages of each process to complement each other, but it also reduces the interference of water on the adsorption process, extends the life of the adsorbent, fully recovers the available components in the oil and gas, and reduces energy consumption.

[0027] 2. This application can effectively reduce the amount of circulating oil and gas in the system by deep cooling the high-concentration desorbed gas, thereby reducing the size of the adsorber, greatly reducing the investment cost of the adsorber, and this technology can greatly reduce the use of liquid nitrogen.

[0028] 3. The nitrogen generated after the liquid nitrogen in this application is gasified can be used for nitrogen sealing and purging of storage tanks, as well as nitrogen purging and vacuum breaking of the adsorption and desorption unit of this system. Compared with common cryogenic units, it reduces the energy consumption of the equipment, and the generated nitrogen can also be recycled.

[0029] 4. This application fully recovers the cooling capacity in the system without causing a large amount of energy waste. The oil and gas recovery efficiency is high and the recovered oil products have a high utilization rate. The liquid phase recovered from the oil and gas can be fully utilized without complicated reprocessing, so that energy can be fully utilized.

[0030] 5. The utility model provides an adsorption, desorption and liquid nitrogen cryogenic system for oil and gas recovery and treatment, which adopts shallow cooling-multi-stage adsorption-vacuum desorption-liquid nitrogen cryogenic process as the treatment process, and can better recover oil and gas components in the vacuum desorption-liquid nitrogen cryogenic step, and the treated tail gas meets the emission standards. The equipment is a skid-mounted device or an integrated device and can operate automatically. At the same time, the equipment has flexible control over the processing capacity, and the absorption efficiency of oil and gas is improved without increasing the floor space. It is ensured that no wastewater is generated after treatment, the energy consumption of the device operation is greatly reduced, the frequency of replacement of the adsorbent is also greatly reduced, the oil and gas recovery efficiency is high, and the recovered oil products have a high degree of use. In addition to the tail gas that meets the emission standards, 100% resource recovery and utilization of effective organic components in oil and gas are achieved, while achieving efficient pollution reduction and carbon reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the utility model.

[0032] Among them, X101 is a flame arrester, E101 is a shallow cooler, C101 is a fan, V101 is a gas-liquid separator, V102A / B is an adsorber, P101 is a production pump, P102 is a vacuum pump, E102A / B / C is a first / second / third stage condenser, V103A\B\C is a gas-liquid separator, V104 is a liquid nitrogen tank, V105 is a liquid storage tank, and P104 is a liquid nitrogen pump; V1 is the air inlet pipeline for external oil and gas to enter the shallow cooler , V2 is the oil and gas pipeline from the shallow cooler to the gas-liquid separator, V3 is the oil and gas pipeline from the gas phase at the top of the gas-liquid separator to the fan, V4 is the oil and gas pipeline from the fan to the adsorber, V5 is the pipeline from the top of the adsorber to the outside for the exhaust gas that meets the emission standards, V6 is the pipeline from the adsorber to the vacuum pump, V7 is the pipeline from the desorbed gas to the primary condenser, V8 is the pipeline from the primary condenser to the gas-liquid separator, V9 is the pipeline from the gas-liquid separator to the secondary condenser, V10 is the pipeline from the secondary condenser to the gas-liquid separator, V11 is the pipeline from the gas-liquid separator to the third-stage condenser, V12 is the pipeline from the third-stage condenser to the gas-liquid separator, V13 is the gas phase pipeline from the gas-liquid separator to the inlet gas-liquid separator, V14 is the pipeline from the liquid storage tank to the inlet gas-liquid separator, V15 is the pipeline for nitrogen to enter the adsorber; L1 is the pipeline from the inlet gas-liquid separator to the production pump, L2 is the gas-liquid The separator is connected to the liquid storage tank, L3 is the pipeline from the liquid storage tank to the production pump, L4 is the liquid inlet pipeline of the liquid nitrogen storage tank, L5 is the pipeline from the liquid nitrogen storage tank to the third-stage condenser, L6 is the pipeline from the third-stage condenser to the second-stage condenser, L7 is the pipeline from the second-stage condenser to the first-stage condenser, L8 is the pipeline from the second-stage condenser to the shallow cooler, L9 is the pipeline from the first-stage condenser to the nitrogen pipeline network, and L10 is the pipeline from the shallow cooler to the nitrogen pipeline network. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0034] An adsorption and desorption system and liquid nitrogen cryogenic system for oil and gas recovery and treatment, the structure of which is as follows Figure 1 As shown, it mainly includes flame arrester X101, a shallow cooling unit composed of a shallow cooler E101, a gas-liquid separator V101, a fan C101 and related connecting pipelines, including an air inlet pipeline V1 from external oil and gas to the shallow cooler, a pipeline V2 from the shallow cooler to the gas-liquid separator, an oil and gas pipeline V3 from the gas phase at the top of the gas-liquid separator to the fan, and a pipeline L1 from the gas-liquid separator liquid phase to the storage tank.

[0035] The adsorption unit consists of the oil and gas pipeline V4 from the fan to the adsorber, the pipeline V5 from the top of the adsorber V102A / V102B to the atmospheric discharge, and the vacuum desorption unit consists of the adsorber V102A / V102B, the vacuum pump P102 and related connecting pipelines, including the pipeline V6 from the adsorber to the vacuum pump, and the pipeline V15 from the nitrogen network to the adsorber.

[0036] It consists of a liquid nitrogen tank V104, a liquid nitrogen pump P104, a primary condenser E102A, a secondary condenser E102B, a tertiary condenser E102C, a gas-liquid separator V103A\V103B\V103C, a liquid storage tank V105, a production pump P103 and related connecting pipelines, including a pipeline V7 from the vacuum pump to the primary condenser, a pipeline V8 from the primary condenser to the gas-liquid separator, a pipeline V9 from the gas-liquid separator to the secondary condenser, a pipeline V10 from the secondary condenser to the gas-liquid separator, a pipeline V11 from the gas-liquid separator to the tertiary condenser, and a pipeline V12 from the gas-liquid separator to the tertiary condenser. The liquid nitrogen deep-cold recovery unit consists of a pipeline V12 from the first-stage condenser to the gas-liquid separator, a pipeline V13 from the gas-liquid separator to the inlet gas-liquid separator, a pipeline L2 from the gas-liquid separator to the liquid storage tank, a pipeline L3 from the liquid storage tank to the production pump, a liquid nitrogen inlet pipeline L4 from the liquid nitrogen tank, a pipeline L5 from the liquid nitrogen pump to the third-stage condenser, a pipeline L6 from the third-stage condenser to the second-stage condenser, a pipeline L7 from the second-stage condenser to the first-stage condenser, a pipeline L8 from the second-stage condenser to the shallow cooler, a pipeline L9 from the first-stage condenser to the nitrogen pipeline network and a pipeline L10 from the shallow cooler to the nitrogen pipeline network.

[0037] The connection description of each part of the system is as follows: the external oil and gas first pass through the flame arrester X101 and then enter the shallow cooling unit, first enter the shallow cooler E101 through the air inlet pipeline V1, and use low-temperature nitrogen as the refrigerant to exchange heat with the oil and gas, reducing the oil and gas temperature to about 5-10°C, and pass the oil and gas into the gas-liquid separator through the pipeline V2. The separated liquid phase is transported to the storage tank through the pipeline L1, and the gas phase is transported to the fan through the pipeline V3, and then the oil and gas are transported to the subsequent units through the fan.

[0038] After being processed by the previous unit, the oil and gas enter the multi-stage adsorption unit. The oil and gas are first transported to the adsorber V102A or V102B through the oil and gas pipeline V4. After a certain period of adsorption treatment by the adsorbent (the adsorbent is activated carbon and silica gel), the clean exhaust gas is discharged through the pipeline V5 leading to the outside world to discharge the exhaust gas that meets the standards. Since the adsorption shares a set of pipelines, one adsorption and one desorption work alternately. When the adsorbent in an adsorber is adsorbed to saturation, the control system automatically switches the adsorption section and starts vacuum desorption of the saturated adsorber at the same time. After the adsorbent is desorbed, it switches back to the adsorption state, thus completing a cycle. This is achieved by the combined action of the vacuum pump P102, the nitrogen inlet pipeline V15, and the pipeline V6 from the adsorber to the vacuum pump.

[0039] The desorbed oil and gas enter the liquid nitrogen cryogenic unit. The desorbed oil and gas first enter the primary condenser E102A through pipeline V7, and after heat exchange with low-temperature nitrogen, enter the gas-liquid separator V103A through pipeline V8. The separated gas phase enters the secondary condenser through pipeline V9, and after heat exchange with low-temperature nitrogen, enters the gas-liquid separator V103B through pipeline V10. The separated gas phase enters the tertiary condenser through pipeline V11. Liquid nitrogen is used as the refrigerant, and the condensation temperature can reach -100 to -160°C, which can be adjusted according to the amount of liquid nitrogen. Then, it enters the gas-liquid separator V103C through pipeline V12. The separated gas phase is passed into the inlet gas-liquid separator through pipeline V13. The separated liquid phase is passed into the liquid storage tank through L2. The volatilized gas phase is transported to the inlet gas-liquid separator V101 through pipeline V14;

[0040] External liquid nitrogen enters the liquid nitrogen storage tank through pipeline L4, and is transported to the third-stage condenser E102C by liquid nitrogen pump P104 through pipeline L5. After heat exchange with oil and gas in the condenser, it is heated and vaporized into low-temperature nitrogen. Then it enters the secondary condenser E102B through pipeline L6. After heat exchange with oil and gas, part of it is transported to the first-stage condenser through pipeline L7, and the other part is transported to the shallow cooler E101 through pipeline L8 to recover the remaining cooling capacity. Finally, it is transported to the nitrogen pipeline network through pipelines L9 and L10 to recover the nitrogen for use.

[0041] The comprehensive process of the whole system is shallow cooling-multi-stage adsorption-vacuum desorption-liquid nitrogen cryogenic recovery. The equipment is a skid-mounted device or an integrated device that can be operated automatically. At the same time, the equipment has flexible control over the processing volume, no wastewater is generated after treatment, the frequency of adsorbent replacement is greatly reduced, the oil and gas recovery efficiency is high, the recycled oil products have a high degree of use, and the energy consumption of the device is reduced; in addition to the exhaust gas that meets the emission standards, 100% of the effective organic components in the oil and gas are recycled and utilized, and efficient pollution reduction and carbon reduction are achieved at the same time.

[0042] Example 1

[0043] This embodiment provides an adsorption-desorption and liquid nitrogen cryogenic system for oil and gas recovery and processing. The structure of the system is as follows: Figure 1 As shown, the system includes a flame arrester X101, a shallow cooling unit, a multi-stage adsorption unit, a vacuum desorption unit and a liquid nitrogen cryogenic recovery unit.

[0044] The shallow cooling unit includes a shallow cooler E101, a gas-liquid separator V101, a fan C101, a production pump P101 and related connecting pipelines, including an air inlet pipeline V1 for external oil and gas to enter the shallow cooler, a pipeline V2 from the shallow cooler to the gas-liquid separator, an oil and gas pipeline V3 from the gas phase at the top of the gas-liquid separator to the fan, and a pipeline L1 for the gas-liquid separator to discharge the liquid phase into the storage tank; the shallow cooler E101 is provided with a refrigerant inlet / outlet and an oil and gas inlet / outlet; the gas-liquid separator V101 is provided with a gas phase inlet, a tank top gas phase outlet, and a tank bottom liquid phase outlet; the gas phase outlet at the top of the gas-liquid separator is connected to the adsorption unit through the fan C101.

[0045] The adsorption unit includes an adsorber V102A / B, a fan C101 and related connecting pipelines, including an oil and gas pipeline V4 from the fan to the adsorber, and a pipeline V5 from the top of the adsorber to the outside for discharging qualified tail gas; the adsorber is provided with a bottom gas phase inlet, a vacuum desorption outlet, a top gas phase outlet, and a nitrogen inlet; the gas discharged through the pipeline from the top gas phase outlet of the adsorber is qualified tail gas.

[0046] The desorption unit includes an adsorber V102A / B, a vacuum pump P102 and related connecting pipelines, including a pipeline V6 from the adsorber to the vacuum pump and a pipeline V15 from the nitrogen network to the adsorber; the vacuum pump P102 is provided with a desorption inlet / outlet; the desorption outlet of the vacuum pump P102 is connected to a liquid nitrogen cryogenic recovery unit via a pipeline.

[0047] The liquid nitrogen cryogenic recovery unit includes a liquid nitrogen tank V104, a liquid nitrogen pump P104, a primary condenser E102A, a secondary condenser E102B, a tertiary condenser E102C, a gas-liquid separator V103A\B\C, a production pump P103 and related connecting pipelines, including a pipeline V7 from the vacuum pump to the primary condenser, a pipeline V8 from the primary condenser to the gas-liquid separator, a pipeline V9 from the gas-liquid separator to the secondary condenser, a pipeline V10 from the secondary condenser to the gas-liquid separator, a pipeline V11 from the gas-liquid separator to the tertiary condenser, a pipeline V12 from the tertiary condenser to the gas-liquid separator, a pipeline V13 from the gas-liquid separator to the inlet gas-liquid separator, a pipeline L2 from the gas-liquid separator to the liquid storage tank, and a liquid nitrogen inlet of the liquid nitrogen tank. Pipeline L4, pipeline L5 from the liquid nitrogen pump to the third-stage condenser, pipeline L6 from the third-stage condenser to the second-stage condenser, pipeline L7 from the second-stage condenser to the first-stage condenser, pipeline L8 from the second-stage condenser to the shallow cooler, pipeline L9 from the first-stage condenser to the nitrogen pipeline network and pipeline L10 from the shallow cooler to the nitrogen pipeline network; the first / second / third-stage condenser E102A / B / C is provided with a refrigerant inlet / outlet and an oil and gas inlet / outlet; the gas-liquid separator V103A\B\C is provided with a gas phase inlet, a top gas phase outlet and a bottom liquid phase outlet, the top gas phase outlet is connected to the inlet gas-liquid separator through a pipeline, the bottom liquid phase outlet is connected to the production pump P103, and the liquid phase is regularly transported out for recovery so that it can be put back into use.

[0048] Specifically, the method comprises the following steps:

[0049] (1) The external oil and gas first pass through the flame arrester and then enter the shallow cooling unit. They first enter the shallow cooling unit through the pipeline and use low-temperature nitrogen as the refrigerant to cool the oil and gas. The outlet temperature of the oil and gas is controlled at about 5°C. The cooled oil and gas are passed into the gas-liquid separator V101. The separated gas phase is discharged from the top gas phase outlet and transported to the absorption unit through the fan C101. The liquid phase at the bottom of the gas-liquid separator is transported to the storage tank through the production pump P101.

[0050] (2) The oil and gas after the shallow cold separation enter the adsorption unit. The oil and gas are first transported into the adsorber through the pipeline, and then continue to be adsorbed by the adsorbent activated carbon for a certain period of time. The clean exhaust gas is discharged through the pipeline in compliance with the standards. Two groups of adsorbers work alternately, one for adsorption and one for desorption. When the adsorbent in an adsorption section is adsorbed to saturation, the control system automatically switches the adsorption section and starts vacuum desorption of the saturated adsorption section at the same time. After the adsorbent is desorbed, it switches back to the adsorption state, thus completing a cycle. This is achieved by the combined action of the vacuum pump, nitrogen pipeline, and desorption oil and gas pipeline.

[0051] (3) The degassing gas enters the liquid nitrogen cryogenic recovery unit, and first enters the primary condenser, the secondary condenser and the tertiary condenser in sequence through the pipeline, condenses the oil and gas to about -100°C, and enters the gas-liquid separator through the pipeline after condensation treatment. The separated gas phase returns to the inlet gas-liquid separator from the top through the pipeline, and the separated liquid phase enters the liquid storage tank from the bottom through the pipeline; the external liquid nitrogen enters the liquid nitrogen tank through the pipeline, and is transported to the refrigerant inlet of the tertiary condenser through the pipeline by the liquid nitrogen pump P104, and is heated and vaporized into low-temperature nitrogen after heat exchange with the oil and gas in the condenser, and then is transported to the refrigerant inlet of the secondary condenser through the pipeline, and after heat exchange with the low-temperature oil and gas, it is again transported to the refrigerant inlet of the shallow cooler through a part of the pipeline, and the other part is transported to the refrigerant inlet of the primary condenser through the pipeline to recover the remaining cold capacity, and finally is transported to the nitrogen pipeline network through the pipeline to recover the nitrogen for use.

[0052] Example 2

[0053] This embodiment provides an adsorption / desorption and liquid nitrogen cryogenic system for oil / gas recovery and processing. The method is the same as that of Embodiment 1 except that the oil / gas condensation temperature in step (3) is replaced by "-150°C".

[0054] Example 3

[0055] The present embodiment provides an adsorption / desorption and liquid nitrogen cryogenic system for oil / gas recovery and processing. The method is the same as that of Embodiment 1 except that the "two groups of adsorbers, one for adsorption and one for desorption, working alternately" in step (2) is changed to "three groups of adsorbers, used in series, two for adsorption and one for desorption, working alternately".

[0056] The adsorption, desorption and liquid nitrogen cryogenic system for oil and gas recovery and processing provided in this application mainly adopts the process of shallow cooling + multi-stage adsorption + vacuum desorption + liquid nitrogen cryogenic. First, the oil and gas generated by loading and unloading and storage are transported into the shallow cooler through a pipeline, and the oil and gas are cooled by low-temperature nitrogen. After the cooling treatment, they are passed into the gas-liquid separation tank. After separation, the gas phase enters the multi-stage adsorber, and multiple adsorbers and vacuum pumps are used to perform cyclic adsorption and desorption alternately. The clean exhaust gas meets the emission standards. The desorbed oil and gas enter the gas-liquid separator after deep cooling, and return to the device inlet through the separated gas phase, and enter the liquid storage tank through the separated liquid phase. If a gas phase is generated in the liquid storage tank, the gas phase will also return to the device inlet, and the liquid phase of the liquid storage tank will be regularly transported out for recovery and put back into use.

[0057] The oil and gas first pass through the flame arrester and then enter the shallow cooler, where low-temperature nitrogen is used for heat exchange. After heat exchange, the oil and gas enter the gas-liquid separation tank, and the liquid phase enters the liquid storage tank. The separated gas phase enters the adsorber through the fan, and the gas after adsorption meets the emission standards. After adsorption to saturation, the control system automatically switches the adsorber and starts vacuum desorption of the saturated adsorber at the same time. After the adsorbent is desorbed, it switches back to the adsorption state, thus completing a cycle. The desorbed oil and gas are passed into the liquid nitrogen cryogenic system. The liquid nitrogen storage tank supplies liquid nitrogen to the cryogenic equipment through the liquid nitrogen pipeline. The liquid nitrogen flow is automatically controlled by the liquid nitrogen regulating valve. Heat is exchanged in the three-stage condensation and gasified into low-temperature nitrogen. The low-temperature nitrogen first recovers cold through the secondary condenser, the primary condensation and the shallow cooler, and then is supplied to the nitrogen pipeline network through the nitrogen recycling device. The condensed oil and gas enter the gas-liquid separator, and the gas phase returns to the oil and gas inlet at the front end of the device. The liquid phase is transported to the low-temperature storage tank for temporary storage. When the liquid level in the storage tank reaches a certain height, the oil-rich pump is started to transport the oil to the designated location in the tank area for further processing. That is, the comprehensive process is a process of shallow cooling + multi-stage adsorption + vacuum desorption + liquid nitrogen deep cooling. The equipment is a skid-mounted device or an integrated device and can operate automatically.

[0058] All liquid phases produced during the cryogenic process are regularly transported out for recycling and put back into use. If they pass the test, they will be re-entered into gasoline, kerosene, residual oil, coal tar, diesel and finished oil storage tanks. If they fail the test, they can be used as blending oil, ship boiler fuel, and heating fuel. In addition to the tail gas that meets the emission standards, 100% of the effective organic components in the oil and gas can be recycled and utilized.

[0059] Since the oil and gas concentration after desorption is very high, the amount of cold required for deep cooling is greatly reduced, and it has a very high recovery rate, which can greatly reduce the circulation accumulation of light components in the system.

[0060] The use of liquid nitrogen for deep cooling greatly reduces the energy consumption of the device, and the amount of liquid nitrogen can be adjusted according to the actual temperature requirements. The nitrogen gas after liquid nitrogen vaporization is not polluted and has a certain pressure. It passes through the nitrogen storage tank and then is adjusted to a pressure slightly higher than the nitrogen pipeline network through the valve group. It enters the tank area nitrogen pipeline network for reuse and is used for nitrogen sealing and purging of storage tanks, as well as nitrogen purging and vacuum breaking of the adsorption and desorption unit of this system.

[0061] The modified set not only effectively utilizes the advantages of each process and makes them complement each other, but also fully recovers the available components in oil and gas, reduces energy consumption and input costs, and achieves efficient pollution reduction and carbon reduction.

[0062] The applicant declares that the utility model illustrates the detailed structural features of the utility model through the above-mentioned embodiments, but the utility model is not limited to the above-mentioned detailed structural features, that is, it does not mean that the utility model must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the utility model, equivalent replacement of the components selected by the utility model, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the utility model.

Claims

1. An adsorption / desorption and liquid nitrogen cryogenic system for oil / gas recovery and treatment, characterized in that: Shallow cooling unit, adsorption and desorption unit and liquid nitrogen cryogenic recovery unit. The shallow cooling unit will initially cool down the oil and gas to separate the gas phase and liquid phase. After separation, the gas phase will enter the adsorption and desorption unit through the fan to remove VOCs, and then the residual gas will enter the liquid nitrogen cryogenic recovery unit through the production pump to recover the residual liquid phase. The shallow cooling unit comprises a flame arrester (X101), a shallow cooler (E101), a gas-liquid separator (V101), a fan (C101) and related connecting pipelines; the oil and gas outlet of the flame arrester is connected to the oil and gas inlet of the shallow cooler, the oil and gas inlet of the shallow cooler is connected to the inlet of the gas-liquid separator, the gas outlet at the top of the gas-liquid separator is connected to the inlet of the fan (C101) of the adsorption and desorption unit; the liquid outlet at the bottom of the gas-liquid separator is connected to the storage tank through a production pump; the cold source circulation pipe of the shallow cooler (E101) is connected to the nitrogen pipeline network; The adsorption-desorption unit comprises two parallel adsorbers (V102A, V102B), the inlet of the adsorber is connected to the residual gas after shallow cooling through a fan, the top outlets of the two parallel adsorbers are respectively connected in parallel to the nitrogen inlet pipe and the discharge outlet pipe, and the adsorbers are filled with adsorbent; the two bottom outlets of the adsorption-desorption unit are connected to the liquid nitrogen deep-cold recovery unit after passing through a vacuum pump; The liquid nitrogen cryogenic recovery unit comprises three-stage condensers (E102A, E102B, E102C) with the same structure, three-stage gas-liquid separators (V103A, V103B, V103C) with the same structure and a liquid nitrogen tank (V104), the three-stage condensers and the three-stage gas-liquid separators are arranged at intervals, the gas phase outlet of each stage condenser is connected to the middle gas phase inlet of the adjacent first-stage gas-liquid separator, the top gas phase outlets of the first-stage and second-stage gas-liquid separators are respectively connected to the middle gas phase inlet of the next-stage gas-liquid separator, the gas phase outlet of the third-stage gas-liquid separator is connected to the middle air inlet of the gas-liquid separator, the lower liquid phase outlets of the three-stage gas-liquid separators are all connected to a liquid storage tank (V105), and the cold source circulation pipe of the condenser is connected to the outlet of the liquid nitrogen tank, so as to provide cold source circulation for adjacent gas-liquid separators respectively.

2. The adsorption / desorption and liquid nitrogen cryogenic system for oil / gas recovery and treatment according to claim 1, characterized in that: The cold source outlet of the three-stage condenser is connected to the inlet of the shallow cooler.

3. The adsorption / desorption and liquid nitrogen cryogenic system for oil / gas recovery and treatment according to claim 1, characterized in that: The liquid nitrogen tank is connected to the three-stage condenser via a liquid nitrogen pump (P104).

4. The adsorption / desorption and liquid nitrogen cryogenic system for oil / gas recovery and treatment according to claim 1, characterized in that: The gas overflow port at the top of the liquid storage tank (V105) is connected to the middle gas inlet of the gas-liquid separator.

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