Carbon dioxide compression system

Abstract

The utility model discloses a carbon dioxide compression system, which can be suitable for large-scale capture, yield increase and energy consumption reduction, and comprises a carbon dioxide desorption tower, a condenser, a first-stage gas-liquid separation tank, a second-stage gas-liquid separation tank, a compressor unit, a third-stage gas-liquid separation tank and a molecular sieve dehydration device which are connected in sequence, the compressor unit comprises a first compressor and a second compressor which are simultaneously connected with the second-stage gas-liquid separation tank and the third-stage gas-liquid separation tank; a heat preservation structure and an elastic clamping piece for fixing the heat preservation structure are arranged on a pipeline for connecting the carbon dioxide desorption tower and the condenser.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of carbon dioxide compression system technical field, especially a kind of carbon dioxide compression system. BACKGROUND

[0002] Carbon dioxide is one of the main reasons of global warming and extreme climate disasters, and in recent years, carbon capture and purification of carbon dioxide have become a hot research topic. Carbon dioxide can be compressed for coal-fired boiler flue gas carbon capture and deep pollution control project, capturing, recycling and utilizing carbon dioxide in power plant exhaust emissions.

[0003] Currently, the most commonly used carbon capture methods are chemical absorption and physical separation. Due to the problems of large capture equipment and high regeneration energy consumption in chemical absorption, traditional physical separation is not suitable for large-scale capture. Therefore, it is necessary to optimize the existing carbon capture method. UTILITY MODEL CONTENT

[0004] In order to overcome the shortcomings of the prior art, one of the purposes of the utility model is to provide a carbon dioxide compression system that can be used for large-scale capture, improve production, and save energy consumption.

[0005] One of the purposes of the utility model is achieved by the following technical solutions:

[0006] A carbon dioxide compression system includes a carbon dioxide stripping tower, a condenser, a first-stage gas-liquid separation tank, a second-stage gas-liquid separation tank, a compressor unit, a third-stage gas-liquid separation tank, and a molecular sieve dehydration device connected in sequence. The compressor unit includes a first compressor and a second compressor connected to the second-stage gas-liquid separation tank and the third-stage gas-liquid separation tank.

[0007] The pipeline connecting the carbon dioxide stripping tower and the condenser is provided with a heat preservation structure and an elastic clamp for fixing the heat preservation structure.

[0008] Further, the heat preservation structure includes a plurality of heat preservation sections wrapped around the pipeline, and a connecting piece is provided between each heat preservation section. The connecting piece includes a first connecting half-ring and a second connecting half-ring, which are detachably connected and form a ring structure, and the cross sections of the first connecting half-ring and the second connecting half-ring are both in the shape of a "T".

[0009] Further, the elastic clamp includes a clasp, a flexible connecting section, an elastic extension section, an adjusting nut, an adjusting screw, and a hook, which are arranged in sequence. The adjusting screw and the adjusting nut are threadedly connected, and the other end of the hook is buckled with the clasp.

[0010] Further, the first compressor comprises a high-pressure motor, a screw main machine, an air inlet filter buffer tank, an oil-gas separator, an after-cooler, an oil cooler, a gas-water separator and a high-efficiency oil remover connected in sequence.

[0011] The air inlet filter buffer tank is connected with the screw main machine through an air inlet valve, the high-pressure motor drives the screw main machine to rotate, an exhaust pipe of the screw main machine is connected with the oil-gas separator, the oil-gas separator is connected with the after-cooler through a minimum pressure valve, an outlet of the after-cooler is connected with the gas-water separator and the high-efficiency oil remover in sequence, an outlet of the high-efficiency oil remover is provided with a gas outlet ball valve, and the oil cooler is communicated with the after-cooler, the first compressor and the oil-gas separator.

[0012] The second compressor has the same structure as the first compressor.

[0013] Further, a circulating pressure relief structure is arranged between the air inlet filter buffer tank and the oil-gas separator.

[0014] Further, the circulating pressure relief structure comprises an equal-diameter four-way pipe, a first pressure relief valve, a second pressure relief valve and a third pressure relief valve, the equal-diameter four-way pipe comprises a first port, a second port, a third port and a fourth port, the first pressure relief valve is communicated with the air inlet filter buffer tank and the first port, the second pressure relief valve is communicated with the air inlet filter buffer tank and the second port, the third pressure relief valve is communicated with the oil-gas separator and the third port, and the fourth port is a standby port.

[0015] A circulating unloading assembly is arranged between the first port and the third port.

[0016] Further, the circulating unloading assembly comprises an unloading ball valve, a main shunt pipe, a vent valve, a primary auxiliary shunt pipe, a plurality of secondary auxiliary shunt pipes, a primary circulating unloading valve and a plurality of secondary circulating unloading valves corresponding to the secondary auxiliary shunt pipes one by one, the primary circulating unloading valve comprises a primary unloading inlet, a primary unloading outlet and a primary circulating port, and each secondary circulating unloading valve comprises a secondary unloading inlet, a secondary unloading outlet and a secondary circulating port.

[0017] Two ends of the unloading ball valve are communicated with the third port and the main shunt pipe respectively, the vent valve is communicated with the main shunt pipe, two ends of the primary auxiliary shunt pipe are communicated with the main shunt pipe and the primary unloading inlet respectively, two ends of each secondary auxiliary shunt pipe are communicated with the main shunt pipe and the corresponding secondary unloading inlet respectively, the primary unloading outlet is communicated with the air inlet filter buffer tank and the first port through a three-way pipe, an auxiliary ball valve is arranged between the primary unloading outlet and the first port, and each secondary unloading outlet is communicated with the air inlet filter buffer tank.

[0018] The primary circulating port and each secondary circulating port are communicated in sequence.

[0019] Further, a backflow port is arranged on the air inlet valve, and an air outlet of the oil-gas separator is communicated with the backflow port through a first backflow pipe.

[0020] Further, the return pipe is provided with a second return pipe in communication, and the second return pipe is in communication with the aftercooler.

[0021] Further, the gas-water separator and the bottom of the high-efficiency oil remover are respectively provided with a first automatic water drainer and a second automatic water drainer, and the water discharge openings of the first automatic water drainer and the second automatic water drainer are in communication with each other.

[0022] Further, the oil outlet of the oil cooler is communicated with a temperature control valve and a cut-off valve, the cut-off valve is communicated with the first compressor through a pipeline, and the temperature control valve is communicated with the oil-gas separator through an oil pump.

[0023] Compared with the prior art, the beneficial effects of the utility model lie in that:

[0024] 1. The coal-fired boiler flue gas carbon capture and pollutant deep treatment project is realized by the parallel compressor, the carbon dioxide in the waste gas discharged by the power plant is captured, recovered and utilized.

[0025] 2. The carbon dioxide capture and recovery process is efficient, energy-saving and stable in equipment operation by the pressure relief and unloading system.

[0026] The above description is only a summary of the technical scheme of the utility model, in order to more clearly understand the technical means of the utility model, the content of the specification can be implemented, and in order to make the above and other purposes, characteristics and advantages of the utility model more obvious and easy to understand, the following preferred embodiments are described in detail, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a schematic view of the embodiment;

[0028] Figure 2 It is a structural schematic view of the connecting ring in the embodiment;

[0029] Figure 3 It is a schematic view of the elastic clamping piece in the embodiment;

[0030] Figure 4 It is a structural schematic view of the connecting ring and the heat preservation section in the embodiment;

[0031] Figure 5 It is a pipeline diagram of the embodiment;

[0032] Figure 6 It is a structural schematic view of the first compressor in the embodiment;

[0033] Figure 7 It is a side view of the first compressor in the embodiment;

[0034] Figure 8 is a partial view of the exhaust valve in the embodiment;

[0035] Figure 9 is a schematic view of the cooperation structure of the primary cycle unloading valve and the secondary cycle unloading valve in the embodiment;

[0036] Figure 10 is a partial schematic view of the embodiment.

[0037] In the figure: 1, carbon dioxide resolving tower; 2, condenser; 21, heat preservation section; 221, first connecting half ring; 222, second connecting half ring; 23, snap ring; 24, flexible connecting section; 25, elastic extension section; 26, adjusting nut; 27, clamping hook; 28, adjusting screw; 3, primary gas-liquid separation tank; 4, secondary gas-liquid separation tank; 51, first compressor; 52, second compressor; 6, tertiary gas-liquid separation tank; 7, molecular sieve dehydration device; 81, high-voltage motor; 82, screw main machine; 821, exhaust pipe; 83, air inlet filter buffer tank; 84, oil-gas separator; 841, minimum pressure valve; 85, after-cooler; 86, oil cooler; 861, oil cut-off valve; 862, temperature control valve; 863, oil pump; 87, gas-water separator; 971, first automatic water drain; 88, high-efficiency oil remover; 881, second automatic water drain; 9, gas outlet ball valve; 89, air inlet valve; 891, backflow port; 892, first backflow pipe; 893, second backflow pipe; 911, first port; 912, second port; 913, third port; 914, fourth port; 921, first pressure relief valve; 922, second pressure relief valve; 923, third pressure relief valve; 93, primary cycle unloading valve; 931, primary unloading inlet; 932, primary unloading outlet; 933, primary cycle port; 934, auxiliary ball valve; 94, secondary cycle unloading valve; 941, secondary unloading inlet; 942, secondary unloading outlet; 943, secondary cycle port; 95, unloading ball valve; 96, main shunt pipe; 97, vent valve; 98, primary auxiliary shunt pipe; 99, secondary auxiliary shunt pipe. DETAILED DESCRIPTION

[0038] In the following, the utility model is further described in combination with the drawings and the specific embodiments, and it should be noted that, under the premise of no conflict, the following described embodiments or technical features can be combined to form new embodiments.

[0039] It should be understood that when an element, or components are referred to as being "on" another element or substrate, it can be directly on another element or intervening elements can also be present. In contrast, when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements can be present. Also, functional or structural terms comparing or describing one element to another are made merely for the purpose of describing a specific embodiment and are not intended to limit the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0041] Embodiment one

[0042] Please refer to Figures 1 to 5 A carbon dioxide compression system, including carbon dioxide desorption tower 1, condenser 2, first-stage gas-liquid separation tank 3, second-stage gas-liquid separation tank 4, compressor set, third-stage gas-liquid separation tank 6, molecular sieve dehydration device 7 and other structures connected in sequence, since the gas volume of a single compressor is about 6000 Nm 3 / h, the flue gas treatment capacity of a coal-fired boiler is 12000 Nm 3 / h, the annual operating time is 8000 hours, and the annual production of carbon dioxide is 200,000 tons. The first compressor 51 and the second compressor 52 are in parallel connection, and need to include the second-stage gas-liquid separation tank 4 and the third-stage gas-liquid separation tank 6. If the production needs to be increased, the parallel compression equipment can be increased in the embodiment.

[0043] The first compressor 51 includes high-voltage motor 81, screw host 82, air inlet filter buffer tank 83, oil-gas separator 84, after-cooler 85, oil cooler 86, gas-water separator 87 and high-efficiency oil remover 88 connected in sequence, and the carbon dioxide is captured through pressurization, separation and cooling, which is high in efficiency and stable in operation.

[0044] In order to improve the recycling rate of heat, the embodiment sets the heat preservation structure and the elastic clamping piece for fixing the heat preservation structure on the pipeline connecting the carbon dioxide desorption tower 1 and the condenser 2. In addition, considering that the equipment is applied to different environments, the heat preservation structure can also be arranged on the pipeline connected with the front and rear of the compressor, the separation tank and the like, so as to ensure that the carbon dioxide in each state can be at the set standard temperature. The design of the elastic clamping piece is convenient for the staff to disassemble, assemble, replace, remove or add the heat preservation structure.

[0045] Specifically, the heat preservation structure includes a plurality of heat preservation sections 21 wrapped around the pipeline. The heat preservation material has a large selectivity. Since polyurethane needs to be sprayed and constructed, it is more troublesome and inconvenient for later adjustment. In the embodiment, rock wool or glass wool and the like are preferably selected. The length of the pipeline is adapted by cutting, and the materials such as aluminum foil can be selectively used. After the heat preservation sections 21 are cut to adapt to each section of the pipeline, they are wrapped and a connecting piece is arranged between each heat preservation section 21 to strengthen the fixation and reduce the gap, thereby ensuring the heat preservation effect.

[0046] The connecting piece is preferably made of a material with poor heat conductivity. It mainly includes a first connecting half ring 221 and a second connecting half ring 222. The first connecting half ring 221 and the second connecting half ring 222 are detachably connected and form a ring structure. The middle part is matched with the size of the pipeline and the pipeline passes through it. Then, the two connecting half rings are buckled to the end face of the adjacent heat preservation section 21 to strengthen the connection and cover the possible exposed parts. The cross section of the first connecting half ring 221 and the second connecting half ring 222 is in the shape of a "T". The connecting piece has the function of wrapping part of the heat preservation section 21. The inner side of the first connecting half ring 221 and the second connecting half ring 222 can be provided with a tapered protrusion embedded in the heat preservation section 21 to strengthen the stability of the connection.

[0047] In addition, the elastic clamping piece in the embodiment is used to enclose the heat preservation section 21 at a suitable position to prevent the heat preservation section 21 from loosening or falling off. Specifically, the elastic clamping piece includes a clamping ring 23, a flexible connecting section 24, an elastic extension section 25, an adjusting nut 26, an adjusting screw 28 and a clamping hook 27 arranged in sequence. The clamping hook 27 is fixed by hooking the clamping ring 23 by its shape, which is also convenient for disassembly. The flexible connecting section 24 enables the elastic clamping piece to have bending ability, which is adapted to the shape of the heat preservation section 21. The appropriate length of the flexible connecting section 24 can also be assembled or selected according to the size of the corresponding pipeline or heat preservation section 21. The elastic extension section 25 can be buckled to the heat preservation section 21 by its elastic deformation recovery to eliminate the excess amount. The elastic extension section 25 is preferably made of a material such as a spring, elastic rubber or other materials with elastic stretching effect. In the embodiment, the flexible elastic rubber material is preferably selected, which has high adhesion. The clamping ring 23, the flexible connecting section 24, the elastic extension section 25 and the adjusting nut 26 are fixedly connected.

[0048] The one end of the adjusting screw 28 is rotatably connected with the hook 27, and the other end is threadedly connected with the adjusting nut 26. The other end of the hook 27 is buckled with the clasp 23. The adjusting screw 28 can be similar to a bolt structure. After the hook 27 is clamped with the clasp 23, the adjusting screw 28 is manually rotated by a tool to tighten the elastic clamping piece and eliminate the excess amount. The adjusting screw 28 can also be disassembled and loosened in the reverse direction to facilitate disassembly.

[0049] The working method of the embodiment is as follows:

[0050] S100: The exhaust gas is separated from carbon dioxide by absorption in the desorption tower;

[0051] S200: The temperature is reduced to 40℃ by the condenser 2;

[0052] S300: The water is removed by the first and second stage gas-liquid separation tanks 4;

[0053] S400: The pressure is increased to 0.2Mpa(G) by the compressor set;

[0054] S500: The liquid water is removed by the third stage gas-liquid separation tank 6;

[0055] S600: The carbon dioxide is captured and recovered by entering the molecular sieve dehydration system.

[0056] Thus, the carbon dioxide in the exhaust gas in the power plant is captured, recovered and utilized.

[0057] Embodiment two

[0058] Please refer to Figures 1 to 10 The embodiment can be based on the embodiment one or the existing carbon dioxide production line. Specifically, the intake filter buffer tank 83 in the embodiment is connected with the screw main machine 82 through the intake valve 89. The high-voltage motor 81 drives the screw main machine 82 to rotate. The exhaust pipe 821 of the screw main machine 82 is connected with the oil-gas separator 84. The oil-gas separator 84 is connected with the after-cooler 85 through the minimum pressure valve 841. The outlet of the after-cooler 85 is sequentially connected with the gas-water separator 87 and the high-efficiency oil remover 88. The outlet of the high-efficiency oil remover 88 is provided with the gas ball valve 9, which is connected with the equipment of the next process.

[0059] In order to improve the operation stability and equipment safety of the embodiment, a circulating pressure relief structure is arranged between the air inlet filtering buffer tank 83 and the oil-gas separator 84. Specifically, the circulating pressure relief structure includes an equal-diameter four-way pipe, a first pressure relief valve 921, a second pressure relief valve 922, and a third pressure relief valve 923. The equal-diameter four-way pipe includes a first port 911, a second port 912, a third port 913, and a fourth port 914. The first pressure relief valve 921 is connected between the air inlet filtering buffer tank 83 and the first port 911. The second pressure relief valve 922 is connected between the air inlet filtering buffer tank 83 and the second port 912. The third pressure relief valve 923 is connected between the oil-gas separator 84 and the third port 913. The fourth port 914 is a standby port. When the pressure in the oil-gas separator 84 is too high, the excess pressure can be returned to the air inlet filtering buffer tank 83 through the opening of the pressure relief valve, and then the air inlet filtering buffer tank 83 is recharged and compressed, so that the pressure in the oil-gas separator 84 is maintained within a set value range. When high pressure is encountered, the third pressure relief valve 923 is opened first, and then the first pressure relief valve 921 and the second pressure relief valve 922 are opened simultaneously for pressure relief. When the medium pressure decreases by a certain value, the pressure relief is stopped. This design is efficient, and the standby port can be selected according to actual needs to select other pressure relief devices for processing.

[0060] In addition, the embodiment also has a circulating unloading assembly between the first port 911 and the third port 913. The circulating unloading assembly includes an unloading ball valve 95, a main shunt pipe 96, a vent valve 97 (used for emptying the medium in special cases), a first auxiliary shunt pipe 98, a plurality of second auxiliary shunt pipes 99, a first circulating unloading valve 93, and a plurality of second circulating unloading valves 94 corresponding to the second auxiliary shunt pipes 99. The first circulating unloading valve 93 includes a first unloading inlet 931, a first unloading outlet 932, and a first circulating port 933. Each second circulating unloading valve 94 includes a second unloading inlet 941, a second unloading outlet 942, and a second circulating port 943. When unloading is not required, the circulating unloading assembly is used to set the system main pressure. When the unloading ball valve 95 is opened and the unloading state is reached, the pressure medium in the oil-gas separator 84 is directly returned to the air inlet filtering buffer tank 83, so that the pressure in the oil-gas separator 84 is reduced to nearly zero, thereby achieving some loop control, such as low-power standby operation without shutdown, and achieving sustained unloading, improving the service life of the oil-gas separator 84, and reducing power consumption.

[0061] Specifically, the two ends of the unloading ball valve 95 are respectively communicated with the third port 913 and the main shunt pipe 96, the vent valve 97 is communicated with the main shunt pipe 96, the two ends of the first auxiliary shunt pipe 98 are respectively communicated with the main shunt pipe 96 and the first unloading inlet 931, the two ends of each second auxiliary shunt pipe 99 are respectively communicated with the main shunt pipe 96 and the corresponding second unloading inlet 941, the first unloading outlet 932 is communicated with the air inlet filter buffer tank 83 and the first port 911 through a tee pipe, and the auxiliary ball valve 934 is arranged between the first unloading outlet 932 and the first port 911. By means of the auxiliary ball valve 934, the pressure relief valve and the unloading valve can be selected to cooperate with each other to solve the problem of special medium pressure being too high. For example, when the medium pressure fluctuates greatly, it may not reach the threshold value at which the pressure relief valve is opened. At this time, the unloading valve is used to continuously release pressure. When the medium pressure is too high for the unloading valve to unload, the pressure relief valve is used to assist in pressure relief. Then, each second unloading outlet 942 is communicated with the air inlet filter buffer tank 83, so that each second unloading can directly send the medium back to the air inlet filter buffer tank 83. The sequential communication between the first circulation port 933 and each second circulation port 943 can realize cyclic unloading, and each unloading valve cooperates with each other to avoid that a certain unloading valve is overloaded and affects the service life. In the embodiment, five unloading valves are arranged, corresponding to four second auxiliary shunt pipes 99.

[0062] In order to absorb excess medium or avoid gas exhaust, the embodiment is provided with a backflow port 891 on the air inlet valve 89, or an air inlet valve 89 with a backflow port 891 is selected, so that the medium can flow back to be compressed again, preventing exhaust and causing resource waste. Specifically, the gas outlet of the oil-gas separator 84 is communicated with the backflow port 891 through the first backflow pipe 892. At the same time, the backflow pipe is also provided with a second backflow pipe 893, which is communicated with the aftercooler 85. In the same way, the exhaust medium is recovered.

[0063] In order to realize automatic drainage, save operation difficulty and reduce work burden, the embodiment is provided with a first automatic drain 971 and a second automatic drain 881 at the bottom of the gas-water separator 87 and the high-efficiency oil remover 88 respectively, the drain outlets of the first automatic drain 971 and the second automatic drain 881 are communicated with each other, and the water outlet can be controlled uniformly through a valve.

[0064] In addition, the oil cooler 86 in the embodiment is connected with the rear cooler 85, the first compressor 51 and the oil-gas separator 84, the water inlet and the water outlet of the oil cooler 86 are connected with the water inlet and the water outlet of the rear cooler 85 one by one, the cooling water in the rear cooler 85 ensures the flowability of the compressor oil at low temperature and the viscosity of the compressor oil is not too low at high temperature to affect the service life of the equipment, and is used for adjusting the temperature of the compressor oil flowing back in each device. The oil outlet of the cooler is connected with a temperature control valve 862 and a cut-off valve 861 respectively, the temperature control valve 862 is a three-way structure, is connected with the oil pump 863 and the oil-gas separator 84, the oil pump 863 supplies oil for the oil cooler 86, the high-temperature compressor oil can be sent to the oil inlet of the oil cooler 86 for cooling through the temperature control valve 862, and then is sent back to the first compressor 51 through the oil outlet, if the compressor oil temperature does not need to be cooled, the temperature control valve 862 can be switched to channel to send the compressor oil back to the first compressor 51 directly for continuous operation. The cut-off valve 861 is connected with the first compressor 51 through a pipeline, and is used for stopping oil supply and opening oil supply, so that too much compressor oil does not enter the first compressor 51 when the equipment starts, and the cut-off valve 861 timely cuts off the oil path when the equipment stops due to high internal air pressure, so that the compressor oil is not sprayed out from the air inlet valve 89.

[0065] The second compressor 52 in the embodiment is the same as the first compressor 51 in structure, and can be increased or decreased according to the yield demand and is connected with each other in parallel, and the embodiment will not be described again.

[0066] The above-mentioned embodiment is only the preferred embodiment of the utility model, and cannot be used to limit the range of the utility model protection, any non-substantial change and replacement of the utility model made by the person skilled in the art on the basis of the utility model belongs to the range of the utility model required to be protected.

Claims

1. A carbon dioxide compression system, characterized by: The carbon dioxide resolving tower (1), the condenser (2), the first-stage gas-liquid separation tank (3), the second-stage gas-liquid separation tank (4), the compressor set, the third-stage gas-liquid separation tank (6) and the molecular sieve dehydration device (7) are sequentially connected. The pipeline connecting the carbon dioxide resolving tower (1) and the condenser (2) is provided with a heat preservation structure and an elastic clamping piece for fixing the heat preservation structure.

2. A carbon dioxide compression system as claimed in claim 1, characterized in that: The heat preservation structure comprises a plurality of heat preservation sections (21) wrapped around the pipeline, and a connecting piece is arranged between each heat preservation section (21). The connecting piece comprises a first connecting half ring (221) and a second connecting half ring (222), which are detachably connected and form an annular structure, and the cross sections of the first connecting half ring (221) and the second connecting half ring (222) are both in the shape of a "T".

3. A carbon dioxide compression system as claimed in claim 2, characterized in that: The elastic clamping piece comprises a clamping ring (23), a flexible connecting section (24), an elastic extension section (25), an adjusting nut (26), an adjusting screw (28) and a clamping hook (27) arranged in sequence. The adjusting screw is threadedly connected with the adjusting nut (26), and the other end of the clamping hook (27) is buckled with the clamping ring (23).

4. A carbon dioxide compression system as claimed in claim 1 or 2 or 3, characterized in that: The first compressor (51) comprises a high-voltage motor (81), a screw main machine (82), an air inlet filter buffer tank (83), an oil-gas separator (84), an aftercooler (85), an oil cooler (86), a gas-water separator (87) and a high-efficiency oil removal device (88) connected in sequence. The air inlet filter buffer tank (83) is connected with the screw main machine (82) through an air inlet valve (89). The high-voltage motor (81) drives the screw main machine (82) to rotate. The exhaust pipe (821) of the screw main machine (82) is connected with the oil-gas separator (84). The oil-gas separator (84) is connected with the aftercooler (85) through a minimum pressure valve (841). The outlet of the aftercooler (85) is sequentially connected with the gas-water separator (87) and the high-efficiency oil removal device (88). The outlet of the high-efficiency oil removal device (88) is provided with a gas ball valve (9). The oil cooler (86) is communicated with the aftercooler (85), the first compressor (51) and the oil-gas separator (84). The second compressor (52) has the same structure as the first compressor (51).

5. A carbon dioxide compression system as claimed in claim 4, characterized in that: A circulating pressure relief structure is arranged between the air inlet filter buffer tank (83) and the oil-gas separator (84). The circulating pressure relief structure comprises an equal-diameter four-way pipe, a first pressure relief valve (921), a second pressure relief valve (922), and a third pressure relief valve (923), the equal-diameter four-way pipe comprises a first port (911), a second port (912), a third port (913), and a fourth port (914), the first pressure relief valve (921) is connected with the air inlet filter buffer tank (83) and the first port (911), the second pressure relief valve (922) is connected with the air inlet filter buffer tank (83) and the second port (912), the third pressure relief valve (923) is connected with the oil-gas separator (84) and the third port (913), and the fourth port (914) is a standby port. The circulating unloading assembly is arranged between the first port (911) and the third port.

6. A carbon dioxide compression system as claimed in claim 5, characterized in that: The circulating unloading assembly comprises an unloading ball valve (95), a main shunt pipe (96), a vent valve (97), a primary auxiliary shunt pipe (98), a plurality of secondary auxiliary shunt pipes (99), a primary circulating unloading valve (93), and a plurality of secondary circulating unloading valves (94) corresponding to the secondary auxiliary shunt pipes (99) one by one, the primary circulating unloading valve (93) comprises a primary unloading inlet (931), a primary unloading outlet (932), and a primary circulating port (933), and each secondary circulating unloading valve (94) comprises a secondary unloading inlet (941), a secondary unloading outlet (942), and a secondary circulating port (943). The two ends of the unloading ball valve (95) are connected with the third port (913) and the main shunt pipe (96) respectively, the vent valve (97) is connected with the main shunt pipe (96), the two ends of the primary auxiliary shunt pipe (98) are connected with the main shunt pipe (96) and the primary unloading inlet (931) respectively, the two ends of each secondary auxiliary shunt pipe (99) are connected with the main shunt pipe (96) and the corresponding secondary unloading inlet (941) respectively, the primary unloading outlet (932) is connected with the air inlet filter buffer tank (83) and the first port (911) through a three-way pipe, and an auxiliary ball valve (934) is arranged between the primary unloading outlet (932) and the first port (911), and each secondary unloading outlet (942) is connected with the air inlet filter buffer tank (83). The primary circulating port (933) and each secondary circulating port (943) are sequentially connected.

7. A carbon dioxide compression system as claimed in claim 6, characterized in that: A backflow port (891) is arranged on the air inlet valve (89), and an air outlet of the oil-gas separator (84) is connected with the backflow port (891) through a first backflow pipe (892).

8. A carbon dioxide compression system as claimed in claim 7, characterized in that: A second backflow pipe (893) is arranged on the backflow pipe, and the second backflow pipe (893) is connected with the aftercooler (85).

9. A carbon dioxide compression system as claimed in claim 6, characterized in that: First and second automatic water drains (971) and (881) are arranged at the bottoms of the gas-water separator (87) and the high-efficiency oil remover (88) respectively, and the water outlets of the first and second automatic water drains (971) and (881) are connected with each other.

10. A carbon dioxide compression system as claimed in claim 6, characterized in that: The oil outlet of the oil cooler (86) is communicated with a temperature control valve (862) and a cut-off valve (861) respectively, the cut-off valve (861) is communicated with the first compressor (51) through a pipeline, and the temperature control valve (862) is communicated with the oil-gas separator (84) through an oil pump (863).

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