Treatment plant for oil field produced gas

Abstract

The application relates to an oilfield produced gas treatment equipment in the technical field of oilfield exploitation, which comprises a multistage compressor assembly, a liquefier, a lithium bromide unit, a separation tank and a pressure swing adsorption device, the multistage compressor assembly is used for carrying out step-by-step compression treatment on oilfield produced gas; the liquefier is used for receiving compressed gas and liquefying to form a gas-liquid mixture; the separation tank is used for carrying out separation treatment on the gas-liquid mixture to obtain liquid carbon dioxide and mixed gas; and the pressure swing adsorption device is used for receiving the mixed gas and carrying out carbon dioxide adsorption treatment to obtain natural gas. The oilfield produced gas treatment equipment can simply and quickly separate carbon dioxide and natural gas in oilfield produced gas, respectively obtains high-purity liquid carbon dioxide and natural gas, greatly improves the recycling rate of carbon dioxide and natural gas, avoids direct discharge of the oilfield produced gas and problems such as complex process flow, high energy consumption and high reagent loss caused by using the existing oilfield produced gas treatment technology.

Description

Technical Field

[0001] This application relates to the field of oilfield development technology, and in particular to a processing device for produced gas from an oilfield. Background Technology

[0002] Oilfield development is an engineering process that extracts crude oil from underground to the surface through drilling, artificial lift, and water injection to replenish formation energy. In the later stages of development, CO2 gas drive is often used to enhance oil recovery. This method utilizes the characteristics of high-pressure supercritical CO2 to mix with crude oil, reduce viscosity, and expand and displace, thereby significantly improving the utilization of remaining underground oil. However, the produced gas generated along with the crude oil during the displacement process contains polluting gases, specifically gases rich in CO2 and mixed with methane, light hydrocarbons, and impurities. These gases cannot be directly emitted. However, existing oilfield produced gas treatment technologies, such as amine absorption and simple condensation / incineration venting, generally suffer from drawbacks such as complex processes, high energy consumption and reagent losses, difficulty in balancing CO2 recovery rate and purity, and equipment corrosion and limited adaptability.

[0003] Therefore, this invention is proposed. Summary of the Invention

[0004] The main objective of this invention is to provide a processing device for produced gas from oil fields, which aims to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, this invention proposes a processing device for produced oilfield gas, comprising: a multi-stage compressor assembly for progressively compressing the produced oilfield gas, wherein the produced oilfield gas is progressively compressed to form compressed gas, the multi-stage compressor assembly includes multiple compressors connected in sequence, and each compressor has a cooler on its outlet side pipeline; a liquefier for receiving the compressed gas and cooling and liquefying it, wherein the compressed gas is cooled and liquefied to form a gas-liquid mixture; a lithium bromide unit for receiving the heat energy released by the produced oilfield gas through each cooler as a driving heat source, and cooperating with the liquefier to remove the heat from the compressed gas, thereby cooling and liquefying the compressed gas; a separator for receiving the gas-liquid mixture and separating it, wherein the gas-liquid mixture is separated to obtain liquid carbon dioxide and a mixed gas; and a pressure swing adsorption (PSA) device for receiving the mixed gas and adsorbing carbon dioxide from it, wherein the mixed gas is purified by adsorption to obtain natural gas.

[0006] By using the oilfield produced gas treatment equipment in this technical solution, compared with existing oilfield produced gas treatment technologies, this invention can simply and quickly separate carbon dioxide and natural gas in oilfield produced gas to obtain high-purity liquid carbon dioxide and natural gas, respectively. Both can be directly exported as products, thereby significantly improving the recovery and utilization rate of carbon dioxide and natural gas. This avoids the direct emission of oilfield produced gas and also avoids the problems of complex process flow, high energy consumption and reagent loss caused by using existing oilfield produced gas treatment technologies.

[0007] In some embodiments of the present invention, a gas-liquid separator is connected to the pipeline between each two adjacent compressors, and the gas-liquid separator is located on the side of the corresponding cooler closer to the downstream compressor.

[0008] In some embodiments of the present invention, at least one of the gas-liquid separators is sequentially connected to a desulfurization device and a drying device between it and a corresponding downstream compressor.

[0009] In some embodiments of the present invention, the lithium bromide unit includes a generator, a condenser, an evaporator, and an absorber; the outlet of each compressor is connected to the tube side of a corresponding cooler, and the shell side of each cooler is connected in series with the tube side of the generator through a first circulation pipeline, the first circulation pipeline being filled with a circulating heat source medium; the outlet of the cooler corresponding to the final stage compressor is connected to the tube side of a liquefier, the shell side of the liquefier is connected in series with the tube side of the evaporator through a second circulation pipeline, the second circulation pipeline being filled with a circulating cold source medium.

[0010] In some embodiments of the present invention, the oilfield produced gas processing equipment further includes a first cold recovery unit, which is located between the cooler corresponding to the final stage compressor and the liquefier. The outlet of the cooler corresponding to the final stage compressor is connected to the tube side of the first cold recovery unit, and the shell side of the first cold recovery unit is connected between the separator and the pressure swing adsorption device.

[0011] In some embodiments of the present invention, the oilfield produced gas processing equipment further includes a second cold recovery unit disposed between each two adjacent compressors, and the second cold recovery unit is located between the corresponding cooler and the gas-liquid separator. The tube side of the second cold recovery unit is connected to the tube side of the corresponding cooler and the gas-liquid separator, and the shell side of the second cold recovery unit is connected between the separator and the pressure swing adsorption device.

[0012] In some embodiments of the present invention, the number of coolers on the outlet side pipeline of each compressor is multiple and connected in series.

[0013] In some embodiments of the present invention, at least a portion of the carbon dioxide gas released by the pressure swing adsorption device is returned to the inlet of the multistage compressor assembly.

[0014] In some embodiments of the present invention, the oilfield produced gas processing equipment further includes a mixer connected to the inlet side of the multi-stage compressor assembly, wherein the oilfield produced gas and the carbon dioxide gas desorbed and released by the pressure swing adsorption device enter the multi-stage compressor assembly through the mixer.

[0015] In some embodiments of the present invention, a buffer separator is connected between the mixer and the multi-stage compressor assembly. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the oilfield produced gas processing equipment of the present invention.

[0017] Figure 2 This is a process diagram of the oilfield produced gas treatment equipment of the present invention for treating oilfield produced gas.

[0018] The labels in the attached diagram represent the following: 1. Liquefaction unit; 2. Separator; 3. Pressure swing adsorption unit; 4. Compressor; 5. Cooler; 6. Gas-liquid separator; 7. Desulfurization unit; 8. Drying unit; 9. Lithium bromide unit; 10. First cold recovery unit; 11. Circulation module; 12. Mixer; 13. Buffer separator. Detailed Implementation

[0019] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0020] In the following description, when referring to the accompanying drawings, the same numbers in different drawings denote the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0021] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, in the description of this application, unless otherwise stated, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0022] This application discloses an oilfield produced gas processing device. For example... Figure 1 As shown, the oilfield produced gas processing equipment includes a multi-stage compressor assembly, a liquefier 1, a separator 2, and a pressure swing adsorption (PSA) device 3. The multi-stage compressor assembly is used to compress the oilfield produced gas stage by stage, forming compressed gas. The liquefier 1 receives the compressed gas and cools and liquefies it, forming a gas-liquid mixture. The separator 2 receives the gas-liquid mixture and separates it, yielding liquid carbon dioxide and a mixed gas. The PSA device 3 receives the mixed gas and adsorbs carbon dioxide from it, resulting in natural gas.

[0023] In this invention, the multi-stage compressor assembly, liquefier 1, separator 2, and pressure swing adsorption device 3 can be connected by pipelines to realize the transportation of materials from upstream to downstream. This invention compresses the produced gas from the oilfield in stages using the multi-stage compressor assembly, and then uses the liquefier 1 to cool and liquefy the compressed gas under high pressure, which can liquefy part of the carbon dioxide gas in the compressed gas, thereby obtaining a gas-liquid mixture including liquid carbon dioxide and mixed gas. Then, the liquid carbon dioxide and mixed gas are separated by the separator 2 to obtain liquid carbon dioxide. High-purity liquid carbon dioxide can be directly exported as a product, such as reinjection for oil displacement. In addition, the pressure swing adsorption device 3 is used to separate and purify the mixed gas to obtain high-purity natural gas, which can also be directly exported as a product, such as for fuel / power generation.

[0024] By using the oilfield produced gas treatment equipment in this technical solution, compared with existing oilfield produced gas treatment technologies, this invention can simply and quickly separate carbon dioxide and natural gas in oilfield produced gas to obtain high-purity liquid carbon dioxide and natural gas, respectively. Both can be directly exported as products, thereby significantly improving the recovery and utilization rate of carbon dioxide and natural gas. This avoids the direct emission of oilfield produced gas and also avoids the problems of complex process flow, high energy consumption and reagent loss caused by using existing oilfield produced gas treatment technologies.

[0025] In some embodiments of the present invention, such as Figure 1 As shown, the multi-stage compressor assembly includes multiple compressors 4 connected in sequence. Each compressor 4 has a cooler 5 on its outlet side pipeline. A gas-liquid separator 6 is connected to the pipeline between each pair of adjacent compressors 4, and the gas-liquid separator 6 is located on the side of the corresponding cooler 5 closer to the downstream compressor.

[0026] In this embodiment, after the compressor 4 compresses the oilfield produced gas, the temperature of the oilfield produced gas increases. The cooler 5 can be used to cool down the high-temperature oilfield produced gas after compression, so as to avoid the temperature of the oilfield produced gas increasing step by step with each compression. This reduces the compression difficulty and ensures the safety of compression. In addition, after the oilfield produced gas is cooled by the compressor 4 and the cooler 5, some of the gas may liquefy. In order to avoid liquid entering the next stage compressor and causing liquid hammer, volume occupation and equipment corrosion, the gas and liquid in the oilfield produced gas can be separated by the gas-liquid separator 6. That is, the gaseous part of the oilfield produced gas continues to pass to the next stage compressor, while the liquid part of the oilfield produced gas is separated and discharged.

[0027] Therefore, in this embodiment, the oilfield produced gas is compressed in stages as follows: the oilfield produced gas first enters the first-stage compressor for first-stage compression, and after compression, it enters the cooler 5 corresponding to the first-stage compressor for cooling and then enters the gas-liquid separator 6 to separate and remove liquid. Then, the oilfield produced gas continues to enter each intermediate-stage compressor, cooler 5, and gas-liquid separator 6 in sequence to complete compression, cooling, and liquid separation respectively. Finally, the oilfield produced gas enters the final-stage compressor for final compression, and after compression, it is cooled by the cooler 5 corresponding to the final-stage compressor.

[0028] In some embodiments of the present invention, the liquid separated from the gas-liquid separator 6 can be depressurized and vaporized and then returned to the primary compressor or collected centrally for use.

[0029] In some embodiments of the present invention, such as Figure 1 As shown, the number of compressors 4 includes, but is not limited to, two, three, four, or five.

[0030] Preferably, there are four compressors 4, meaning that the produced gas from the oilfield undergoes four stages of compression treatment. The produced gas from the oilfield after the first three stages of compression treatment is cooled and then separated into liquids, and the produced gas after the last stage of compression treatment is cooled to finally obtain compressed gas.

[0031] In some embodiments of the present invention, such as Figure 1 As shown, the produced gas from the oilfield undergoes four stages of compression. The pressures of the produced gas after each stage of compression are 0.35~0.4 MPa, 0.8~1.2 MPa, 2.5~3 MPa, and 7~8 MPa, respectively.

[0032] Preferably, the pressures of the produced gas after the first-stage compression, second-stage compression, and third-stage compression are 0.38 MPa, 1 MPa, and 2.7 MPa, respectively. The pressure of the produced gas after the last-stage compression can be reasonably designed as needed, such as a final compressed gas pressure of 7.38 MPa or greater.

[0033] In some embodiments of the present invention, such as Figure 1 As shown, at least one gas-liquid separator 6 is sequentially connected to a desulfurization device 7 and a drying device 8 between it and the corresponding downstream compressor.

[0034] In this embodiment, the desulfurization device 7 can remove sulfide gases (such as H2S) from the produced gas from the oilfield, ensuring that the final natural gas product is clean and avoiding pollution and risks caused by the combustion of sulfide gases; the drying device 8 is mainly used to remove moisture from the produced gas from the oilfield, which not only avoids the subsequent moisture from affecting the cooling and liquefaction of compressed gas, but also improves the purity of the product liquid carbon dioxide and the product natural gas.

[0035] In some embodiments of the present invention, such as Figure 1 As shown, the desulfurization unit 7 and the drying unit 8 can be sequentially installed after the primary compressor, the secondary compressor, or the tertiary compressor.

[0036] Preferably, the desulfurization device 7 and the drying device 8 are arranged sequentially after the three-stage compressor, that is, between the three-stage compressor and the final stage compressor, and between the gas-liquid separator 6 and the final stage compressor.

[0037] In some embodiments of the present invention, such as Figure 1 As shown, multiple desulfurization devices 7 and drying devices 8 can be installed and connected in parallel on the pipeline.

[0038] In this embodiment, when one or more of the desulfurization devices 7 or drying devices 8 are used to remove sulfur or water from the produced gas from the oilfield, the remaining desulfurization devices 7 or drying devices 8 can be regenerated, thereby operating in a cycle.

[0039] In some embodiments of the present invention, the number of desulfurization devices 7 or drying devices 8 includes, but is not limited to, two, three or four, and each desulfurization device 7 or drying device 8 can achieve the removal or regeneration of sulfur or water through independently controlled valves.

[0040] In some embodiments of the present invention, such as Figure 1 As shown, the oilfield produced gas processing equipment also includes a lithium bromide unit 9. The lithium bromide unit 9 is used to receive the heat energy released by the oilfield produced gas through each cooler 5 as a driving heat source, and works with the liquefier 1 to remove the heat of the compressed gas to cool the liquefied compressed gas. The lithium bromide unit 9 includes a generator, a condenser, an evaporator, and an absorber. The outlet of each compressor 4 is connected to the tube side of the corresponding cooler 5. The shell side of each cooler 5 is connected in series with the tube side of the generator through a first circulation pipeline. The first circulation pipeline is filled with a circulating heat source medium. The outlet of the last stage compressor corresponding to the cooler 5 is connected to the tube side of the liquefier 1. The shell side of the liquefier 1 is connected in series with the tube side of the evaporator through a second circulation pipeline. The second circulation pipeline is filled with a circulating cold source medium.

[0041] In this embodiment, the generator receives heat released from the heat source medium to heat the dilute lithium bromide solution, causing the water in the solution to vaporize and separate high-temperature, high-pressure refrigerant water vapor, while simultaneously generating a concentrated lithium bromide solution, thereby reducing the temperature of the compressed oilfield produced gas to the required temperature. The condenser cools the high-temperature, high-pressure water vapor generated by the generator into room-temperature, high-pressure liquid water, releasing condensation heat to prepare for subsequent cold source generation. The evaporator depressurizes and cools the liquid water in the condenser to form low-temperature, low-pressure wet steam. The wet steam absorbs heat and vaporizes in the evaporator, absorbing heat from the cold source medium to release the cold source, ultimately cooling the compressed gas (carbon dioxide) to its liquefaction temperature. The absorber reabsorbs the low-temperature, low-pressure water vapor vaporized in the evaporator back into the concentrated lithium bromide solution to generate a dilute lithium bromide solution, completing the regeneration of the absorbent and refrigerant. The dilute solution can be sent back to the generator to absorb heat again, achieving a cycle.

[0042] In some embodiments of the present invention, such as Figure 2 As shown, there are multiple coolers 5 on the outlet side of each compressor 4, which are connected in series.

[0043] It should be understood that each cooler 5 is used in conjunction with the lithium bromide unit 9, that is, the lithium bromide unit 9 uses its generator in conjunction with multiple coolers after each stage compressor to perform stage-by-stage cooling of the oilfield produced gas after each stage of compression.

[0044] In this embodiment, after the oilfield produced gas is compressed by the compressor 4, its temperature is gradually reduced to the temperature required for the next stage of compression. On the one hand, compared to reducing the oilfield produced gas from the highest temperature to the lowest temperature all at once, the gradient reduction can reduce the difficulty of cooling the oilfield produced gas. On the other hand, compared to reducing the oilfield produced gas from the highest temperature to the lowest temperature all at once, the gradient heat extraction of the heat source medium co-generator can greatly improve the heat extraction efficiency and heat extraction ratio, reduce heat loss, and improve the utilization rate of compression heat.

[0045] In some embodiments of the present invention, the number of coolers 5 on the outlet side pipeline of each compressor 4 includes, but is not limited to, two, three, or four.

[0046] Preferably, there are two coolers 5 on the outlet side of each compressor 4, which improves the efficiency of reducing the temperature of produced gas in the oilfield, increases the utilization rate of compression heat, and effectively controls the complexity of the equipment.

[0047] Furthermore, on the outlet side of each compressor 4, there are two coolers, with the upstream cooler having a higher heat extraction ratio than the downstream cooler. That is, the temperature V1 of the oilfield produced gas reduced by the upstream cooler is greater than the temperature V2 reduced by the downstream cooler.

[0048] In some embodiments of the present invention, the number of generators in the lithium bromide unit 9 includes, but is not limited to, one or more.

[0049] For example, when there is only one generator, the single generator can be used to collect all the interstage waste heat for centralized heat extraction; when there are multiple generators, the generators can be set up one-to-one with the coolers 5, that is, each cooler 5 has a generator, and each generator only absorbs the waste heat at the location of the corresponding single-stage compression and single cooler. Multiple generators work independently and their parameters can be adjusted individually. Finally, they are all connected to the same set of condenser, evaporator and absorber to complete the working fluid circulation, so that the generator is matched with each compressor 4 and the multiple coolers after each compressor 4, realizing the complete step-by-step heat extraction between stages, thereby further improving the heat extraction efficiency and heat extraction ratio, reducing heat loss and improving the compression heat utilization rate.

[0050] In some embodiments of the present invention, such as Figure 1 As shown, the oilfield produced gas processing equipment also includes a first cold recovery unit 10. The first cold recovery unit 10 is located between the cooler corresponding to the final stage compressor and the liquefier 1. The outlet of the cooler corresponding to the final stage compressor is connected to the tube side of the first cold recovery unit 10, and the shell side of the first cold recovery unit 10 is connected between the separator 2 and the pressure swing adsorption device 3.

[0051] In this embodiment, the mixed gas separated by the separator 2 is a low-temperature gas cooled by the liquefier 1. The temperature of the mixed gas is lower than that of the compressed gas that will enter the liquefier 1 and there is a high temperature difference. By setting a first cold recovery unit 10 on the inlet side of the liquefier 1, the compressed gas passes through the tube side of the first cold recovery unit 10 and the mixed gas passes through the shell side of the first cold recovery unit 10, which can complete the heat exchange between the compressed gas and the mixed gas. This achieves the purpose of pre-cooling the compressed gas by using the cold recovery of the mixed gas. This not only raises the temperature of the mixed gas, so that the pressure swing adsorption device 3 can better remove carbon from the mixed gas, but also completes the gradient pre-cooling of the compressed gas in conjunction with the cooler 5. This further reduces the difficulty of liquefying the compressed gas in the liquefier 1 and improves the liquefaction efficiency.

[0052] In some embodiments of the present invention, the oilfield produced gas processing equipment further includes a second cold recovery unit (not shown) disposed between every two adjacent compressors 4, and the second cold recovery unit is located between the corresponding cooler and the gas-liquid separator 6. The tube side of the second cold recovery unit is connected to the tube side of the corresponding cooler and the gas-liquid separator 6, and the shell side of the second cold recovery unit is connected between the separator tank 2 and the pressure swing adsorption device 3.

[0053] In this embodiment, a second cold recovery unit is installed between adjacent compressors 4, located on the outlet side of cooler 5. Utilizing the temperature difference between the interstage compressed oilfield produced gas and the mixed gas, the compressed oilfield produced gas passes through the tube side of the second cold recovery unit, while the mixed gas passes through the shell side. This allows for heat exchange between the compressed gas and the compressed oilfield produced gas, achieving the goal of cooling the compressed oilfield produced gas by recovering the temperature of the mixed gas. This allows the mixed gas to achieve a temperature increase without external heat input, enabling the pressure swing adsorption device 3 to better remove carbon from the mixed gas. Furthermore, the interstage cooler, in conjunction with the second cold recovery unit, completes the gradient pre-cooling of the compressed oilfield produced gas. This reduces the load on the interstage cooler while the second cold recovery unit shares part of the cooling load on the interstage compressed oilfield produced gas, thus reducing the temperature difference between the high and low temperatures. This allows the interstage cooler to extract heat from the interstage compressed oilfield produced gas with higher efficiency and a higher heat extraction ratio, further improving the utilization of compression heat and achieving efficient operation of the oilfield produced gas processing equipment while reducing energy consumption.

[0054] In some embodiments of the present invention, the flow rate of the mixed gas through each second cold recovery unit can be controlled independently, such as by setting valves separately. Specifically, the flow rate can be adjusted according to the heat extraction power of the interstage cooler on the corresponding interstage compressed oilfield produced gas. This ensures that the interstage cooler can extract heat from the interstage compressed oilfield produced gas at a high ratio, and also ensures that after the mixed gas cools the interstage compressed oilfield produced gas, the temperature of the interstage compressed oilfield produced gas can meet the compression requirements of the next stage compressor.

[0055] In some embodiments of the present invention, the first cold recovery unit 10 and the second cold recovery unit may be set up simultaneously or only one of them may be set up.

[0056] Preferably, the first cold recovery unit 10 and the second cold recovery unit are installed simultaneously and connected in parallel between the separator 2 and the pressure swing adsorption device 3 via pipelines. The flow rate of the mixed gas through the first cold recovery unit 10 and each of the second cold recovery units can be adjusted as needed.

[0057] In some embodiments of the present invention, the oilfield produced gas processing equipment further includes an expansion and depressurization device (not shown), and the expansion and depressurization device may be located downstream of the first cold recovery unit 10 and / or the second cold recovery unit.

[0058] In this embodiment, after the mixed gas is introduced into the first cold recovery unit 10 or the second cold recovery unit, it can be introduced into the expansion and depressurization device to reduce the pressure of the mixed gas and release energy to do work. The cooling fan is driven to rotate by the transmission mechanism to perform secondary purging and precooling on the compressed gas passing through the first cold recovery unit 10, or to assist the second cold recovery unit in purging and cooling the interstage compressed oilfield produced gas passing through the second cold recovery unit, so as to achieve precise temperature control. At the same time, the depressurized mixed gas can better meet the adsorption and removal of carbon dioxide by the pressure swing adsorption device 3.

[0059] In some embodiments of the present invention, the expansion depressurization device may be provided downstream of the first cold recovery unit 10 or downstream of the second cold recovery unit, or both.

[0060] In some embodiments of the present invention, such as Figure 1 As shown, at least a portion of the carbon dioxide gas released by the pressure swing adsorption device 3 is returned to the inlet of the multi-stage compressor assembly.

[0061] In this embodiment, by sending the carbon dioxide adsorbed by the pressure swing adsorption device 3 back to the first-stage compressor and mixing it with the produced gas from the oilfield for further processing, the carbon dioxide content in the produced gas from the oilfield can be increased, which can then be used to stabilize the process and improve recovery efficiency.

[0062] In some embodiments of the present invention, the proportion of carbon dioxide released by the pressure swing adsorption device 3 after desorption can be reasonably designed according to process requirements, for example, it can be partially or completely returned to the first-stage compressor.

[0063] Preferably, 20% of the carbon dioxide released by the pressure swing adsorption device 3 is returned to the device, and the remaining carbon dioxide released by desorption can be collected and utilized.

[0064] In some embodiments of the present invention, such as Figure 1As shown, the carbon dioxide released by the pressure swing adsorption device 3 through desorption can be precisely controlled by the circulation module 11 to control its reflux rate.

[0065] Furthermore, the circulation module 11 may include structures such as a circulation pump, control valve, flow meter and check valve. The circulation pump installed on the pipeline drives the carbon dioxide backflow, the control valve and flow meter precisely control the flow rate, and the check valve prevents the oilfield produced gas from flowing into the pressure swing adsorption device 3.

[0066] In some embodiments of the present invention, such as Figure 1 As shown, the pressure swing adsorption device 3 is provided in multiple units and is connected in parallel with the separation tank 2.

[0067] In this embodiment, when one or more pressure swing adsorption devices 3 are used to remove carbon dioxide from the mixed gas, the remaining pressure swing adsorption devices 3 can depressurize to desorb and release carbon dioxide, thereby operating in a cycle.

[0068] In some embodiments of the present invention, the number of pressure swing adsorption devices 3 includes, but is not limited to, two, three or four, and each pressure swing adsorption device 3 can achieve carbon dioxide adsorption or desorption through an independently controlled valve.

[0069] In some embodiments of the present invention, such as Figure 1 As shown, the oilfield produced gas processing equipment also includes a mixer 12, which is connected to the inlet side of the multi-stage compressor assembly. The oilfield produced gas and the carbon dioxide gas desorbed and released by the pressure swing adsorption device 3 enter the multi-stage compressor assembly through the mixer 12.

[0070] In this embodiment, the mixer 12 can uniformly mix the produced gas from the oilfield with the carbon dioxide gas desorbed and released by the pressure swing adsorption device 3, thereby avoiding the deviation of feed or composition fluctuations in subsequent equipment such as the compressor 4 and cooler 5, and ensuring process stability.

[0071] In some embodiments of the present invention, such as Figure 1 As shown, a buffer separator 13 is connected between the mixer 12 and the multi-stage compressor assembly.

[0072] In this embodiment, the buffer separator 13 can separate the liquid that may be present in the produced gas from the oil field and the carbon dioxide gas desorbed and released by the pressure swing adsorption device 3, thereby better protecting the first-stage compressor.

[0073] The following describes the oilfield produced gas processing equipment in further detail with reference to specific embodiments.

[0074] Example 1 like Figure 2As shown, the temperature of the produced gas (raw material gas) from the oilfield is 40 ℃, the pressure is 135 kPa, and the flow rate is 1.000e+004 Nm³. 3 / h (i.e., 10,000 standard cubic meters per hour).

[0075] The produced gas from the oilfield first enters the mixer 12 along with the carbon dioxide desorbed from the pressure swing adsorption device 3 for uniform mixing. Then, the produced gas (material 36') enters the buffer separator 13 for gas-liquid separation. The produced gas (material 2') enters the first-stage compressor for compression, while the liquid (material 3') is discharged from the buffer separator 13.

[0076] The first-stage compressor drive power (Q-100) is 580 kW. The compressed interstage oilfield produced gas (material 4') passes through the first cooler (material 6') and the second cooler (material 5') in sequence, and is heated by the generator of the lithium bromide unit 9. The heat load of the first cooler (Q-111) is 381.2 kW (representing the heat removed from the gas), and the heat load of the second cooler is Q-112. Q-112 can be calculated by combining Q-100 and Q-111 with the heat loss rate.

[0077] Then the produced gas from the oilfield (material 5') enters the gas-liquid separator 6 for gas-liquid separation. The produced gas from the oilfield (material 8') enters the secondary compressor for compression, and the liquid (material 9') is discharged from the gas-liquid separator 6.

[0078] The driving power of the second-stage compressor (Q-101) is 568 kW. The compressed interstage compressed oilfield produced gas (material 7') passes through the first cooler (material 10') and the second cooler (material 11') in sequence, and is heated by the generator of the lithium bromide unit 9. The heat load of the first cooler (Q-113) is 391.1 kW (representing the heat removed from the gas), and the heat load of the second cooler is Q-114. Q-114 can be calculated by combining Q-101 and Q-113 with the heat loss rate.

[0079] Then the produced gas from the oilfield (material 11') enters the gas-liquid separator 6 for gas-liquid separation. The produced gas from the oilfield (material 14') enters the three-stage compressor for compression, and the liquid (material 15') is discharged from the gas-liquid separator 6.

[0080] The three-stage compressor drive power (Q-108) is 541.8 kW. The compressed interstage oilfield produced gas (material 21') passes through the first cooler (material 12') and the second cooler (material 13') in sequence, and is heated by the generator of the lithium bromide unit 9. The heat load of the first cooler (Q-115) is 408.5 kW (representing the heat removed from the gas), and the heat load of the second cooler is Q-116. Q-116 can be calculated by combining Q-108 and Q-115 with the heat loss rate.

[0081] Then, the produced gas from the oilfield (material 13') enters the gas-liquid separator 6 for gas-liquid separation. The produced gas from the oilfield (material 22') enters the desulfurization unit 7 and the drying unit 8 for desulfurization and dehydration treatment, while the liquid (material 27') is discharged from the gas-liquid separator 6. After being processed by the desulfurization unit 7 and the drying unit 8, the produced gas from the oilfield (material 16') enters the four-stage compressor for compression treatment, and the removed impurities (material 17') are discharged.

[0082] The four-stage compressor drive power (Q-117) is 497.3 kW. The compressed gas (material 20') obtained by the final compression passes through the first cooler (material 32') and the second cooler (material 34') in sequence, and is heated by the generator of the lithium bromide unit 9. The heat load of the first cooler (Q-118) is 492 kW (representing the heat removed from the gas), and the heat load of the second cooler is Q-119. Q-119 can be calculated by combining Q-117 and Q-118 with the heat loss rate.

[0083] Then the compressed gas (material 34') enters the first cold recovery unit 10 and is pre-cooled by the mixed gas (material 30'). After pre-cooling, the compressed gas (material 35') enters the liquefier 1 and is cooled and liquefied by the evaporator of the lithium bromide unit 9 to form a gas-liquid mixture (material 29'). The heat load (Q-120) of the liquefier 1 is 814.1 kW (representing the heat removed from the gas).

[0084] The gas-liquid mixture (material 29') then enters the separator 2 for separation, yielding liquid carbon dioxide and a mixed gas (material 30'). The mixed gas (material 30') then passes through the first cold recovery unit 10 (material 37') and enters the pressure swing adsorption unit 3 for separation and purification, yielding natural gas. After desorption and release of carbon dioxide in the pressure swing adsorption unit 3 (material 26'), 20% is uniformly refluxed back to the mixer 12, ultimately yielding the product liquid carbon dioxide and the product natural gas. The liquefied CO2 (liquid carbon dioxide) has a temperature of 10 ℃, a pressure of 7260 kPa, and a flow rate of 9249 Nm³. 3The flow rate is 1.676e+004 kg / h (i.e., 10,000 standard cubic meters per hour); the natural gas temperature is 32 ℃, the pressure is 7500 kPa, and the flow rate is 535.1 Nm³. 3 / h (i.e., 10,000 standard cubic meters per hour).

[0085] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A processing device for produced gas from an oilfield, characterized in that, include: A multi-stage compressor assembly is used to perform staged compression processing on oilfield produced gas, wherein the oilfield produced gas is compressed into compressed gas through staged compression. The multi-stage compressor assembly includes multiple compressors connected in sequence, and each compressor is equipped with a cooler on the outlet side of the pipeline. A liquefier is used to receive the compressed gas and cool and liquefy the compressed gas to form a gas-liquid mixture. The lithium bromide unit is used to receive the heat energy released by the oilfield produced gas through each cooler as a driving heat source, and works with the liquefier to remove the heat of the compressed gas in order to cool and liquefy the compressed gas. A separation tank is used to receive the gas-liquid mixture and separate the gas-liquid mixture to obtain liquid carbon dioxide and a mixed gas, respectively. A pressure swing adsorption (PSA) device is used to receive the mixed gas and perform carbon dioxide adsorption treatment on the mixed gas, so that natural gas is obtained after the carbon dioxide is removed by adsorption treatment.

2. The oilfield produced gas processing equipment according to claim 1, characterized in that, A gas-liquid separator is connected to the pipeline between each pair of adjacent compressors, and the gas-liquid separator is located on the side of the corresponding cooler closer to the downstream compressor.

3. The oilfield produced gas processing equipment according to claim 2, characterized in that, At least one of the gas-liquid separators is sequentially connected to a desulfurization device and a drying device between it and the corresponding downstream compressor.

4. The oilfield produced gas processing equipment according to claim 2, characterized in that, The lithium bromide unit includes a generator, a condenser, an evaporator, and an absorber; The outlet of each compressor is connected to the tube side of the corresponding cooler, and the shell side of each cooler is connected in series with the tube side of the generator through a first circulation pipeline. The first circulation pipeline is filled with a circulating heat source medium. The outlet of the final stage compressor corresponding to the cooler is connected to the tube side of the liquefier. The shell side of the liquefier is connected in series with the tube side of the evaporator through a second circulation pipeline, which is filled with a circulating cold source medium.

5. The oilfield produced gas processing equipment according to claim 4, characterized in that, It also includes a first cold recovery unit, which is located between the cooler corresponding to the final stage compressor and the liquefier. The outlet of the cooler corresponding to the final stage compressor is connected to the tube side of the first cold recovery unit, and the shell side of the first cold recovery unit is connected between the separator and the pressure swing adsorption device.

6. The oilfield produced gas processing equipment according to claim 4, characterized in that, It also includes a second cold recovery unit disposed between each two adjacent compressors, and the second cold recovery unit is located between the corresponding cooler and the gas-liquid separator. The tube side of the second cold recovery unit is connected to the tube side of the corresponding cooler and the gas-liquid separator, and the shell side of the second cold recovery unit is connected between the separator and the pressure swing adsorption device.

7. The oilfield produced gas processing equipment according to claim 4, characterized in that, The number of coolers on the outlet side of each compressor is multiple and connected in series.

8. The oilfield produced gas processing equipment according to claim 1, characterized in that, At least a portion of the carbon dioxide gas released by the pressure swing adsorption device during desorption flows back to the inlet of the multi-stage compressor assembly.

9. The oilfield produced gas processing equipment according to claim 6, characterized in that, It also includes a mixer connected to the inlet side of the multi-stage compressor assembly, through which the oilfield produced gas and the carbon dioxide gas desorbed and released by the pressure swing adsorption device enter the multi-stage compressor assembly.

10. The oilfield produced gas processing equipment according to claim 9, characterized in that, A buffer separator is connected between the mixer and the multi-stage compressor assembly.

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