Precise realization of carbon dioxide pipeline impurity proportioning filling device and filling method

Abstract

This invention relates to a filling device and method for accurately achieving the mixing ratio of impurities in carbon dioxide pipelines. The filling device includes a main pipeline, an impurity gas cylinder, a carbon dioxide gas source container, a filling pump, a platform scale, a weighbridge, an impurity filling pipeline, and a carbon dioxide filling pipeline. One end of each of the impurity filling pipeline and the carbon dioxide filling pipeline is connected to the main pipeline, and the other end of the impurity filling pipeline is connected to the impurity gas cylinder. The other end of the carbon dioxide filling pipeline is connected to the carbon dioxide gas source container. The impurity filling pipeline is equipped with a first valve and a first pressure reducing valve, and the carbon dioxide filling pipeline is equipped with a filling pump, a second valve, and a third valve. The impurity gas cylinder is mounted on the platform scale, and the carbon dioxide gas source container is mounted on the weighbridge. The filling device of this invention can achieve accurate filling of different types and contents of impurities required for carbon dioxide pipeline experiments under different operating conditions.

Description

Technical Field

[0001] This invention relates to the field of CO2 pipeline engineering technology, specifically to a filling device and method for accurately achieving the mixing ratio of impurities in carbon dioxide pipelines. Background Technology

[0002] Currently, China's carbon capture and sterilization (CCUS) technology is still in its infancy, and large-scale commercial supercritical CO2 pipelines are scarce. Only some oilfields have constructed short-distance, small-diameter CO2 pipelines to enhance oil recovery. Therefore, there is an urgent need to conduct large-scale industrial-grade CO2 pipeline experiments to study important aspects such as pipeline safety operation patterns and leakage consequences analysis, providing guidance for national CO2 pipeline construction. However, due to the relatively low impurity content in the pipeline medium, how to prepare supercritical CO2 fluid media containing impurities in industrial-grade experimental devices, and thus accurately achieve experimental conditions at specific pressures and temperatures, remains a pressing challenge. Summary of the Invention

[0003] In order to solve one or more technical problems existing in the prior art, the present invention provides a filling device and filling method for accurately achieving the mixing ratio of impurities in carbon dioxide pipelines.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A filling device for accurately realizing the impurity ratio of carbon dioxide pipeline, comprising a main pipeline, an impurity gas cylinder, a carbon dioxide gas source container, a filling pump, a platform scale, a weighbridge, an impurity filling pipeline, and a carbon dioxide filling pipeline. One end of the impurity filling pipeline and the carbon dioxide filling pipeline are respectively connected to the main pipeline, the other end of the impurity filling pipeline is connected to the impurity gas cylinder, and the other end of the carbon dioxide filling pipeline is connected to the carbon dioxide gas source container. The impurity filling pipeline is provided with a first valve and a first pressure reducing valve, and the carbon dioxide filling pipeline is provided with a filling pump, a second valve, and a third valve. The impurity gas cylinder is placed on the platform scale, and the carbon dioxide gas source container is placed on the weighbridge.

[0005] The beneficial effects of the present invention are: the filling device of the present invention can accurately fill different types and contents of impurities required for carbon dioxide pipeline experiments under different working conditions.

[0006] Based on the above technical solution, the present invention can be further improved as follows.

[0007] Furthermore, the second valve and the third valve are respectively located upstream and downstream of the injection pump.

[0008] Furthermore, the first valve is located downstream of the first pressure-reducing valve.

[0009] Furthermore, a main input pipeline is connected to the main pipeline, and one end of the impurity injection pipeline and the carbon dioxide injection pipeline are both connected to the main input pipeline. A fourth valve is provided on the main input pipeline.

[0010] Furthermore, it also includes a carbon dioxide cylinder and a purging pipeline, one end of which is connected to the carbon dioxide cylinder and the other end of which is connected to the main pipeline.

[0011] The advantage of adopting the above-mentioned further solution is that the main pipeline can be purged before injection.

[0012] Furthermore, the purging pipeline is equipped with a second pressure reducing valve and a fifth valve.

[0013] Furthermore, a pressure relief pipeline is also connected to the main pipeline, and a sixth valve is installed on the pressure relief pipeline.

[0014] Furthermore, the main pipeline is covered with an electric heating layer, which is then covered with an insulation layer. The main pipeline is also equipped with a temperature sensor and a pressure sensor, which are electrically connected to the PID control system.

[0015] The beneficial effects of adopting the above-mentioned further scheme are: the pressure value and pressure rise rate in the main pipeline can be monitored by the PID control system, the electric heating layer is self-temperature controlled and integrated into the PID control system, high-power heating will be used in the initial stage of heating, and when the pressure value is close to the pressure value required for the experiment, the PID control system will automatically reduce the heating power or even stop heating until the temperature and pressure in the main pipeline reach the specified working conditions.

[0016] The method for accurately achieving the impurity ratio in carbon dioxide pipelines, using the aforementioned filling device, includes the following steps:

[0017] When both carbon dioxide and impurities need to be added under specified operating conditions:

[0018] S1, the mass of impurities to be added under specified operating conditions is ΔM 杂质 First, zero the platform scale, then place the impurity gas cylinder on the scale and record its initial weight m. 杂质_0 Adjust the first pressure reducing valve to the first preset pressure, open the first valve, and open the impurity gas cylinder for impurity filling. Monitor the scale reading constantly. When the initial weight m of the impurity gas cylinder... 杂质_0 The scale reading m during the filling process 杂质_1 The difference (m) 杂质_0 -m 杂质_1 The mass of added impurities is equal to ΔM. 杂质 When the impurity gas cylinder is closed, the first valve and the first pressure reducing valve should also be closed.

[0019] S2, The mass of carbon dioxide required to be added under specified operating conditions is △M CO2 First, zero the weighbridge, then place the carbon dioxide gas source container on the weighbridge and record the initial weight m of the carbon dioxide gas source container. CO2_0 Open the second and third valves, start the filling pump to add carbon dioxide, and constantly monitor the changes in the weighbridge reading. When the initial weight m of the carbon dioxide source container... CO2_0 The weighbridge reading during the filling process (m) CO2_1 The difference (m) CO2_0 -m CO2_1 ) equals the mass of carbon dioxide added ΔM CO2 At that time, close the second and third valves;

[0020] Under specified operating conditions, no impurities need to be added; when only carbon dioxide is added, only S2 is required.

[0021] The beneficial effects of the present invention are: the filling method of the present invention can achieve precise filling of various types and contents of impurities under different pressure and temperature conditions in a large-scale industrial-grade supercritical CO2 experimental device.

[0022] Furthermore, under specified operating conditions, the mass of impurities △M needs to be added. 杂质 =α 杂质 ρ 混合_工况 V1+ρ 杂质_加注 V2, where α 杂质 For the first preset mass fraction, ρ 混合_工况 ρ is the density of the mixture of carbon dioxide and impurities under specified operating conditions. 杂质_加注 V1 represents the density of impurities during the filling process, V2 represents the volume of the main pipeline, and V2 represents the volume of the impurities flowing through the filling path. The required carbon dioxide mass ΔM to be filled under specified operating conditions. CO2 =α CO2 ρ 混合_工况 V1+ρ CO2_加注 (V2+V3)-ρ CO2_常温常压 ×V1, where α CO2 For the second preset mass fraction, ρ 混合_工况 ρ is the density of the mixture of carbon dioxide and impurities under specified operating conditions. CO2_加注 ρ represents the density of carbon dioxide during refueling. CO2_常温常压 V1 is the density of carbon dioxide at normal temperature and pressure, V2 is the volume of the main pipeline, V3 is the volume of the carbon dioxide flow path during the filling process, and V4 is the volume of the filling pump chamber.

[0023] The beneficial effect of adopting the above-mentioned further solution is that the mass of impurities and carbon dioxide to be added can be calculated in advance according to the specified working conditions, which facilitates subsequent system operation.

[0024] Furthermore, it also includes S3, where the main pipeline is equipped with an electric heating layer, a temperature sensor, and a pressure sensor. When the electric heating layer on the main pipeline is turned on, the PID control system electrically connected to the electric heating layer is activated. The pressure value fed back to the PID control system by the pressure sensor on the main pipeline is used to control the start and stop of temperature control and the heating power of the electric heating layer until the pressure and temperature in the main pipeline reach the temperature and pressure required by the specified working conditions. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the filling device for accurately achieving the impurity ratio in a carbon dioxide pipeline according to the present invention.

[0026] The attached diagram lists the components represented by each number as follows:

[0027] 1. Main pipeline; 2. Impurity gas cylinder; 3. Carbon dioxide gas source container; 4. Filling pump; 5. Platform scale; 6. Weighbridge; 7. Impurity filling pipeline; 8. Carbon dioxide filling pipeline; 9. First valve; 10. First pressure reducing valve; 11. Second valve; 12. Third valve; 13. Main input pipeline; 14. Fourth valve; 15. Purge pipeline; 16. Second pressure reducing valve; 17. Fifth valve; 18. Pressure relief pipeline; 19. Sixth valve; 20. Carbon dioxide cylinder; 21. Electric heating layer; 22. Insulation layer; 23. Temperature sensor; 24. Pressure sensor; 25. PID control system. Detailed Implementation

[0028] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0029] like Figure 1 As shown in the figure, this embodiment of a refueling device for accurately achieving the mixing ratio of impurities in a carbon dioxide pipeline includes a main pipeline 1, an impurity gas cylinder 2, a carbon dioxide gas source container 3, a refueling pump 4, a platform scale 5, a weighbridge 6, an impurity refueling pipeline 7, and a carbon dioxide refueling pipeline 8. One end of the impurity refueling pipeline 7 and the carbon dioxide refueling pipeline 8 are respectively connected to the main pipeline 1, the other end of the impurity refueling pipeline 7 is connected to the impurity gas cylinder 2, and the other end of the carbon dioxide refueling pipeline 8 is connected to the carbon dioxide gas source container 3. The impurity refueling pipeline 7 is provided with a first valve 9 and a first pressure reducing valve 10, and the carbon dioxide refueling pipeline 8 is provided with a refueling pump 4, a second valve 11, and a third valve 12. The impurity gas cylinder 2 is mounted on the platform scale 5, and the carbon dioxide gas source container 3 is mounted on the weighbridge 6.

[0030] like Figure 1 As shown, in this embodiment, the second valve 11 and the third valve 12 are respectively located upstream and downstream of the filling pump 4. The first valve 9 is located downstream of the first pressure reducing valve 10.

[0031] One optional solution in this embodiment is, as follows: Figure 1 As shown, a main input pipeline 13 is connected to the main pipeline 1. One end of the impurity injection pipeline 7 and the carbon dioxide injection pipeline 8 are both connected to the main input pipeline 13. A fourth valve 14 is provided on the main input pipeline 13.

[0032] like Figure 1 As shown, the filling device in this embodiment also includes a carbon dioxide cylinder 20 and a purging pipeline 15. One end of the purging pipeline 15 is connected to the carbon dioxide cylinder 20, and the other end of the purging pipeline 15 is connected to the main pipeline 1. The main pipeline can be purged before filling.

[0033] like Figure 1 As shown, the purging pipeline 15 in this embodiment is equipped with a second pressure reducing valve 16 and a fifth valve 17.

[0034] like Figure 1 As shown, in this embodiment, the main pipeline 1 is also connected to a pressure relief pipeline 18, and the pressure relief pipeline 18 is equipped with a sixth valve 19.

[0035] like Figure 1 As shown, in this embodiment, the main pipeline 1 is covered with an electric heating layer 21, which is further covered with an insulation layer 22. A temperature sensor 23 and a pressure sensor 24 are also installed on the main pipeline 1. The electric heating layer 21 and the pressure sensor 24 are electrically connected to a PID control system 25. The PID control system can monitor the pressure value and pressure rise rate within the main pipeline. High-power heating is used in the initial heating stage. When the pressure value approaches the required experimental pressure, the PID control system automatically reduces the heating power or even stops heating until the temperature and pressure within the main pipeline reach the specified operating conditions. Specifically, the electric heating layer can be made of an electric heating wire or an electric heating tape.

[0036] The filling device in this embodiment can accurately fill different types and contents of impurities required for experiments under different working conditions. The main pipeline is heated by electric heat tracing and is equipped with temperature monitoring and PID self-regulating temperature control. This can prevent the inaccurate control of the CO2 state in the pipeline due to excessive heating power or failure to shut off the heating in time.

[0037] This embodiment also provides a method for accurately achieving the impurity ratio in a carbon dioxide pipeline, which is implemented using the above-mentioned filling device and includes the following steps:

[0038] When both carbon dioxide and impurities need to be added under specified operating conditions:

[0039] S1, the mass of impurities to be added under specified operating conditions is ΔM 杂质First, zero the platform scale 5, then place the impurity gas cylinder 2 on the platform scale 5 and record the initial weight m of the impurity gas cylinder 2. 杂质_0 Adjust the first pressure reducing valve 10 to the first preset pressure, open the first valve 9, and open the impurity gas cylinder 2 to fill with impurities. Monitor the reading on the platform scale 5 constantly. When the initial weight m of the impurity gas cylinder 2... 杂质_0 The scale reading m during the filling process 杂质_1 The difference (m) 杂质_0 -m 杂质_1 The mass of added impurities is equal to ΔM. 杂质 At the same time, close the impurity gas cylinder 2, and simultaneously close the first valve 9 and the first pressure reducing valve 10;

[0040] S2, The mass of carbon dioxide required to be added under specified operating conditions is △M CO2 First, zero the weighbridge 6, then place the carbon dioxide gas source container 3 on the weighbridge 6 and record the initial weight m of the carbon dioxide gas source container 3. CO2_0 Open the second valve 11 and the third valve 12, and start the filling pump 4 to add carbon dioxide. Monitor the weighbridge 6 reading closely. When the initial weight m of the carbon dioxide source container 3... CO2_0 The weighbridge reading during the filling process (m) CO2_1 The difference (m) CO2_0 -m CO2_1 ) equals the mass of carbon dioxide added ΔM CO2 At that time, close the second valve 11 and the third valve 12;

[0041] Under specified operating conditions, no impurities need to be added; when only carbon dioxide is added, only S2 is required.

[0042] It also includes S3, where the main pipeline is equipped with an electric heating layer 21, a temperature sensor 23, and a pressure sensor 24. The electric heating layer 21 on the main pipeline 1 is turned on, and the PID control system 25, electrically connected to the electric heating layer 21, is activated. The pressure value fed back to the PID control system 25 from the pressure sensor 24 on the main pipeline 1 controls the start and stop of temperature control and the heating power of the electric heating layer 21, until the pressure and temperature within the main pipeline 1 reach the specified operating conditions. The temperature within the main pipeline 1 can be manually read using the temperature sensor 23.

[0043] Furthermore, under specified operating conditions, the mass of impurities △M needs to be added. 杂质 =α 杂质 ρ 混合_工况 V1+ρ 杂质_加注 V2, where α 杂质 For the first preset mass fraction, ρ 混合_工况 ρ is the density of the mixture of carbon dioxide and impurities under specified operating conditions. 杂质_加注V1 represents the density of impurities during the refueling process, V2 represents the volume of the main pipeline, and V3 represents the volume of the impurity flow path during the refueling process (including the volume of the impurity refueling pipeline and the total input pipeline); the mass of carbon dioxide to be refueled under specified operating conditions is ΔM. CO2 =α CO2 ρ 混合_工况 V1+ρ CO2_加注 (V2+V3)-ρ CO2_常温常压 ×V1, where α CO2 For the second preset mass fraction, ρ 混合_工况 ρ is the density of the mixture of carbon dioxide and impurities under specified operating conditions. CO2_加注 ρ represents the density of carbon dioxide during refueling. CO2_常温常压 V1 represents the density of carbon dioxide at normal temperature and pressure, V2 represents the volume of the main pipeline, V3 represents the volume of the carbon dioxide flow path during the carbon dioxide refueling process (including the volume of the carbon dioxide refueling pipeline and the total input pipeline), and V4 represents the volume of the refueling pump chamber. The required amount of impurities and carbon dioxide to be refueled can be pre-calculated according to specified operating conditions, facilitating subsequent system operation.

[0044] In this embodiment, the density (ρ) of the CO2 and impurity mixture under the specified operating conditions is... 混合_工况 The result is calculated using the GERG-2008 high-precision gas state equation, and the calculation results are more accurate than those of the traditional PR or RK equations. The selection of the gas source container needs to be based on the mass obtained from the calculation method, making full use of gas resources and saving costs. For weighbridges and platform scales, the range and accuracy should be selected based on the total weight of the gas source container when it is full, thus saving costs and improving measurement accuracy.

[0045] Another optional solution in this embodiment is to ensure that all valves, pumps, and power supplies are closed before refueling. Then, open valves 17 and 19, adjust the second pressure reducing valve 16 to a suitable pressure, and open the carbon dioxide cylinder 20. Use the self-pressurization of the carbon dioxide cylinder 20 to purge the main pipeline 1. The purging time needs to be determined based on the CO2 purity of the gas sample detected at the vent. This purges all air and other impurities from the main pipeline 1, ensuring that only CO2 remains inside. After purging, simultaneously close the carbon dioxide cylinder 20, valve 17, and valve 19.

[0046] The filling method of this embodiment enables precise filling of various impurities of different types and contents under different pressure and temperature conditions in a large-scale industrial-grade supercritical CO2 experimental device. This filling method pre-calculates the required mass of impurities and the amount of carbon dioxide to be added. Utilizing the principle of mass conservation of identical substances in different states within a confined space, the required mass of CO2 and impurities is calculated based on the pipeline volume and the density of CO2 or impurities under specified operating conditions. Furthermore, the loss of mass source after filling is accurately calculated by considering the volumes of the main pipeline, filling pipeline, and pump. In addition to the calculation method, this filling method also includes an experimental procedure to achieve accurate weighing and reach the experimental operating point. This experimental procedure involves placing the gas source container on a weighbridge and platform scale, weighing it while filling. Filling stops once the mass difference obtained by the calculation method is reached, thus achieving precise mass control. Finally, a PID control system for the pipeline and temperature and pressure monitoring are used to achieve PID control, ensuring that the CO2 in the pipeline reaches the specified operating point.

[0047] Test case

[0048] Taking a CO2 volume fraction of 98% and an O2 impurity volume fraction of 2% as an example, converting to mass fraction... Main pipeline volume V1 = 1000L, CO2 injection pipeline volume V 2_CO2 =2L, impurity filling pipeline volume V 2_杂质 =0.2L, pump body volume V3=1L, experimental pressure P_ 实验 =15MPa, experimental temperature T_ 实验 At 50℃, the CO2 injection pressure P_ CO2_加注 =2.2MPa, CO2 injection temperature T_ CO2_加注 = -20℃, O2 injection pressure P_ O2_加注 =4MPa, O2 injection temperature T_ CO2_加注 =20℃,

[0049] First, based on the temperature and pressure under specified operating conditions, the density ρ of the CO2 and impurity mixture at that temperature and pressure is determined using the GERG2008 equation. 混合_工况 =670.91kg / m 3 And the densities of CO2 and impurities during refueling are ρ CO2_加注 =1033.2kg / m 3 , ρ 杂质_加注 =55.297kg / m 3 , Then the mass of CO2 required for refueling, ΔM, is calculated. CO2 = 98.357% × 670.91 × 1 + 1033.2 × (0.002 + 0.001) - 1.8393 × 1 = 661.093 kg and ΔM杂质_O2 =1.643%×670.91×1+55.297×0.0002=11.034kg.

[0050] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0052] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0054] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0055] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for accurately achieving the impurity ratio in carbon dioxide pipeline filling, characterized in that, The filling device is used, which includes a main pipeline, an impurity gas cylinder, a carbon dioxide gas source container, a filling pump, a platform scale, a weighbridge, an impurity filling pipeline, and a carbon dioxide filling pipeline. One end of the impurity filling pipeline and the carbon dioxide filling pipeline are respectively connected to the main pipeline, and the other end of the impurity filling pipeline is connected to the impurity gas cylinder. The other end of the carbon dioxide filling pipeline is connected to the carbon dioxide gas source container. The impurity filling pipeline is equipped with a first valve and a first pressure reducing valve. The carbon dioxide filling pipeline is equipped with a filling pump, a second valve, and a third valve. The impurity gas cylinder is placed on the platform scale, and the carbon dioxide gas source container is placed on the weighbridge. The refueling method includes the following steps: When both carbon dioxide and impurities need to be added under specified operating conditions: S1, the mass of impurities to be added under specified operating conditions is... First, zero the platform scale and place the impurity gas cylinder on it, recording the initial weight m of the impurity gas cylinder. 杂质_0 Adjust the first pressure reducing valve to the first preset pressure, open the first valve, and open the impurity gas cylinder for impurity filling. Monitor the scale reading constantly. When the initial weight m of the impurity gas cylinder... 杂质_0 The scale reading m during the filling process 杂质_1 The difference (m) 杂质_0 -m 杂质_1 (equal to the mass of added impurities) When the impurity gas cylinder is closed, the first valve and the first pressure reducing valve should also be closed. S2, the mass of carbon dioxide required to be added under specified operating conditions is [amount missing]. First, zero the weighbridge, then place the carbon dioxide gas source container on the weighbridge and record the initial weight m of the carbon dioxide gas source container. CO2_0 Open the second and third valves, start the filling pump to add carbon dioxide, and constantly monitor the changes in the weighbridge reading. When the initial weight m of the carbon dioxide source container... CO2_0 The weighbridge reading during the filling process (m) CO2_1 The difference (m) CO2_0 -m CO2_1 (equal to the mass of carbon dioxide added) At that time, close the second and third valves; Under specified operating conditions, no impurities need to be added; when adding carbon dioxide, only S2 is required. The required amount of impurities to be added under specified operating conditions ,in, The first preset quality score, The density of the mixture of carbon dioxide and impurities under specified operating conditions. V1 represents the density of impurities during the filling process, V2 represents the volume of the main pipeline, and V1 represents the volume of the impurities flowing through the filling path. The required mass of carbon dioxide to be added under specified operating conditions is also given. ,in, The second preset quality score, The density of the mixture of carbon dioxide and impurities under specified operating conditions. This refers to the density of carbon dioxide during the refueling process. V1 is the density of carbon dioxide at normal temperature and pressure, V2 is the volume of the main pipeline, V3 is the volume of the carbon dioxide flow path during the filling process, and V4 is the volume of the filling pump chamber.

2. The method for accurately achieving the impurity ratio in a carbon dioxide pipeline according to claim 1, characterized in that, The second valve and the third valve are respectively located upstream and downstream of the injection pump; the first valve is located downstream of the first pressure reducing valve.

3. The method for accurately achieving the impurity ratio in a carbon dioxide pipeline according to claim 1, characterized in that, The main pipeline is connected to a total input pipeline. One end of the impurity injection pipeline and the carbon dioxide injection pipeline are both connected to the total input pipeline. A fourth valve is provided on the total input pipeline.

4. The method for accurately achieving the impurity ratio in a carbon dioxide pipeline according to claim 1, characterized in that, It also includes a carbon dioxide cylinder and a purging pipeline, one end of which is connected to the carbon dioxide cylinder and the other end of which is connected to the main pipeline.

5. The method for accurately achieving the impurity ratio in a carbon dioxide pipeline according to claim 4, characterized in that, The purging pipeline is equipped with a second pressure reducing valve and a fifth valve.

6. The method for accurately achieving the impurity ratio in a carbon dioxide pipeline according to claim 1, characterized in that, The main pipeline is also connected to a pressure relief pipeline, and a sixth valve is installed on the pressure relief pipeline.

7. The method for accurately achieving the impurity ratio in a carbon dioxide pipeline according to claim 1, characterized in that, The main pipeline is covered with an electric heating layer, which is then covered with an insulation layer. The main pipeline is also equipped with a temperature sensor and a pressure sensor, which are electrically connected to the PID control system.

8. The method for accurately achieving the impurity ratio in a carbon dioxide pipeline according to any one of claims 1 to 7, characterized in that, It also includes S3, where the main pipeline is equipped with an electric heating layer, a temperature sensor, and a pressure sensor. When the electric heating layer on the main pipeline is turned on, the PID control system electrically connected to the electric heating layer is activated. The pressure value fed back to the PID control system by the pressure sensor on the main pipeline is used to control the start and stop of temperature control and the heating power of the electric heating layer until the pressure and temperature in the main pipeline reach the temperature and pressure required by the specified working conditions.

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