A design method for active spin-scrubbing pig for natural gas pipelines

Abstract

This invention relates to the field of natural gas pipeline cleaning technology, specifically disclosing a design method for an active vortex purging pig for natural gas pipelines. The method utilizes the pressure difference between the front and rear ends of the outer cylinder to generate an active rotational torque through an impeller, driving a central shaft coaxially connected to the impeller to rotate. This central shaft then drives the rotation of the front-end branched jet tubes, forming a vortex jet that powerfully purges the pipe wall and uses the vortex effect to move dust and even accumulated liquid forward. The method determines the number and inclination angle of the jet tubes; calculates the bypass area of ​​the jet tubes; calculates the bypass rate and operating speed of the active vortex purging pig; and calculates the minimum standard-condition natural gas pipeline throughput required given the operating speed of the active vortex purging pig. This method solves the problems of small purging range, poor purging effect on the pipe wall, and insufficient jet intensity of conventional active vortex purging pigs, while also implementing algorithms for calculating the bypass rate and the operating speed of the active vortex purging pig.

Description

Technical Field

[0001] This invention relates to the field of natural gas pipeline cleaning technology, and more specifically, to a design method for an active vortex purging pig for natural gas pipelines. Background Technology

[0002] Natural gas pipeline transportation is an important mode of transporting oil and natural gas, offering advantages such as large transport capacity, high speed, and low cost and energy consumption. During the construction of natural gas pipelines, solid debris such as welding slag, iron filings, and soil may enter the pipeline, as may residual liquid moisture from pressure testing. During operation, natural gas may carry fine particles, moisture, hydrocarbons, and other impurities into the pipeline. Over time, corrosive substances may accumulate in the pipeline. These contaminants can reduce the efficiency of natural gas pipeline transportation and, in severe cases, cause blockages, affecting the safe and stable operation of the pipeline network. Therefore, pipeline cleaning is an essential step in the construction and operation of natural gas pipelines to ensure safe operation, reduce corrosion, and improve economic efficiency.

[0003] Traditional active vortex purging pigs, such as pigging balls, have a simple structure but are prone to clogging at tees, resulting in poor cleaning performance. While cup-type active vortex purging pigs have a wider range of applications and better cleaning results, active vortex purging pigs, based on the cup-type design, incorporate jet orifices. These orifices spray high-pressure gas to flush away accumulated impurities in natural gas pipelines, achieving even better cleaning results. Currently, jet cleaning technology is mainly used for dewaxing crude oil and natural gas pipelines and removing condensate from subsea natural gas pipelines. However, there is limited research on its application in removing free water from saturated gas and small amounts of dust from gathering and transporting natural gas pipelines. Common jet cleaning techniques typically use axial or diffusion jets to purge the natural gas pipeline upstream of the active vortex purging pig, which is not optimal for natural gas pipelines with significant dust and contamination. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a design method for an active vortex purging pig for natural gas pipelines; it solves the problems of small purging range, poor purging effect on pipe wall, and insufficient jet intensity of conventional active vortex purging pigs, and at the same time realizes the bypass rate calculation algorithm and the active vortex purging pig running speed calculation algorithm.

[0005] The solution adopted by this invention to solve the technical problem is:

[0006] A design method for an active vortex purging pig for natural gas pipelines, the active vortex purging pig comprising an outer cylinder, a central shaft coaxially arranged within and around the outer cylinder, a plurality of jet tubes disposed at one end of the central shaft and communicating with the central shaft, an impeller mounted on the outside of the central shaft, and a cup assembly mounted on the outer cylinder; the end of each jet tube away from the central shaft faces the natural gas pipeline for natural gas transportation; the central shaft is rotatably coupled to the outer cylinder; a plurality of vent holes communicating with the interior of the central shaft are provided on the central shaft; the vent holes are located on the side of the impeller assembly near the jet tubes; specifically including the following steps:

[0007] Step S1: Utilize the pressure difference between the front and rear ends of the outer cylinder to generate an active rotational torque through the impeller, driving the central shaft, which is coaxially connected to the impeller, to rotate; install a jet pipe, which is connected to the interior of the central shaft, at the output end of the central shaft;

[0008] Step S2: Several waist-shaped holes are set on the central shaft to guide the natural gas passing through the impeller into the central shaft and form a gas flow channel through the jet pipe;

[0009] Step S3: The central shaft drives the front branch assembly of the jet tube to rotate, forming a swirling jet that powerfully blows the tube wall and uses the swirling effect to drive dust and even accumulated liquid forward.

[0010] Step S4: Determine the number of jet tubes and the tilt angle of the jet tubes relative to the central axis;

[0011] Step S5: Calculate the bypass area of ​​the jet tube;

[0012] Step S6: Calculate the bypass rate and operating speed of the active cyclone purging pig;

[0013] Step S7: Calculate the minimum standard-condition natural gas pipeline throughput required given the operating speed of the active vortex purging pig.

[0014] In some possible implementations, the formula for calculating the active rotational torque generated by the impeller in step S1 is shown in equation (1):

[0015] T=ρQ(R2V 2t -R1V 1t (1);

[0016] Where T is the impeller torque;

[0017] Q represents the flow rate through the impeller; R1 and R2 are the radii of the inner and outer rings of the impeller, respectively.

[0018] V 1t This represents the tangential component of the absolute velocity of the fluid flowing into the impeller from the inner ring of the impeller.

[0019] V 2t This represents the tangential component of the absolute velocity of the fluid flowing into the impeller on the outer ring of the impeller.

[0020] In some possible implementations, the pressure difference between the front and rear ends of the outer cylinder in step S1 is calculated as follows:

[0021] P=ρgH (2);

[0022]

[0023] P = Tω (4);

[0024] Where H is the capacity obtained by a unit mass of fluid passing through the impeller;

[0025] g is the acceleration due to gravity;

[0026] P represents the pressure difference across the active vortex purging pig.

[0027] In some possible implementations, step S4 specifically refers to:

[0028] First, the number of jet tubes is initially determined. Then, 3D modeling software is used to establish the flow domain space of the jet tube outlet at different inclination angles. Flow field simulation is performed using flow field calculation software. Based on the simulation results, the swirling purging intensity and purging range at different inclination angles are analyzed. Finally, the inclination angle of the jet tube relative to the central axis is determined in combination with the processing requirements of the jet tube.

[0029] Then, the number of jet tubes was changed; the flow field analysis was performed again, and the number of jet tubes was determined by analyzing the swirling purging intensity and purging range under different numbers of nozzles.

[0030] The final tilt angle and number of jet tubes are obtained.

[0031] In some possible implementations, step S5 specifically refers to:

[0032] Step S51: Calculation of the maximum bypass area of ​​the jet tube:

[0033]

[0034] Among them, A hmax This represents the maximum bypass area of ​​the jet tube;

[0035] A is the internal cross-sectional area of ​​the natural gas pipeline;

[0036] F f The frictional force between the diaphragm cup and the inner wall of the natural gas pipeline during operation;

[0037] m is the mass of the active vortex purging pig;

[0038] P1 is the pressure at the end of the active swirling purge cleaner furthest from the jet tube;

[0039] P3 is the pressure at the end of the active vortex purging cleaner near the jet tube.

[0040] Step S52: Calculation of minimum bypass area of ​​jet tube;

[0041]

[0042] Among them, A hmin K represents the minimum bypass area of ​​the jet tube. p ρ is the pressure loss coefficient of natural gas flowing through the jet orifice of the active swirl purge pig; Q2 is the natural gas density; T2 is the natural gas flow rate; T is the gas temperature before throttling; c P is the critical temperature. c P is the critical pressure. r For comparison of pressure; T r For comparison temperature; c p Let Pr be the specific heat of natural gas; f(Pr,Tr) is calculated as follows:

[0043]

[0044] In some possible implementations, the bypass rate of the active swirl purge cleaner is calculated in step S6, specifically by calculating the total area of ​​all jet tube perforations using formula (8).

[0045]

[0046] in,

[0047] K p This is the kinetic energy correction factor, an empirical constant;

[0048] ρ h The density of natural gas under operating conditions;

[0049] Q represents the operating natural gas flow rate;

[0050] A h This represents the total area of ​​the injection holes on the jet nozzle.

[0051] Active vortex purging pig bypass rate The calculation is as follows:

[0052]

[0053] In some possible implementations, the frictional force F between the cup in the cup assembly and the inner wall of the natural gas pipeline during operation... f Calculated as;

[0054] F f =2πrp L p μ f N f (10);

[0055] Where, r p The inner radius of the pipe;

[0056] L p The contact length between the cup assembly and the pipe;

[0057] μ f The coefficient of friction of the leather cup;

[0058] The clamping force between the diaphragm and the natural gas pipeline in the diaphragm assembly is calculated by equation (11);

[0059]

[0060] Where E is the elastic modulus of the diaphragm; δ p For the interference fit of the leather cup; γ i Poisson's ratio for leather bowls;

[0061] In equation (8), the kinetic energy correction coefficient K is calculated from equation (12);

[0062]

[0063] In the formula d h The diameter of the jet nozzle is denoted as .

[0064] In some possible implementations, the operating speed V of the active cyclone purging pig in step S6 is... pig Performing calculations specifically refers to:

[0065]

[0066] In the formula,

[0067] V g —Natural gas flow velocity;

[0068] φ——Bypass rate of active vortex purging pig, (0~1);

[0069] α — Inclination angle of the natural gas pipeline;

[0070] ρ bp —Natural gas density under operating conditions;

[0071] In some possible implementations, step S7 specifically refers to:

[0072] Set the active swirl purging pig speed, assume the most extreme working condition, the natural gas pipeline inclination angle is 90° uphill, calculate the natural gas compressibility factor Z under a given pressure, calculate the natural gas density under the working condition, and calculate the natural gas working speed V using formula (13). g ;

[0073] Calculate the minimum standard-condition natural gas pipeline throughput Q0 required given a fixed operating speed of the active vortex purging pig;

[0074]

[0075] Where T0 is the standard temperature and P0 is the standard pressure.

[0076] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0077] This invention fully utilizes the pressure difference before and after the cleaning process. Based on the active rotational torque generated by the impeller, it drives the front-end branched combined jet pipe to rotate, thereby forming a swirling jet at the front end of the active swirling purging pig. This jet can powerfully purge the pipe wall and use the swirling effect to move dust and even accumulated liquid forward, greatly improving the cleaning effect. It can also be used for uniform spraying of coatings inside natural gas pipelines. This invention is designed to ensure the reliable and stable operation of cleaning operations on large-diameter natural gas pipelines, preventing safety accidents. At the same time, the developed bypass rate calculation algorithm and active swirling purging pig operating speed calculation algorithm can quickly perform jet bypass rate design calculations and calculate and predict the jet cleaning operation time and required gas volume.

[0078] This invention uses natural gas as the medium within a natural gas pipeline. An impeller and hollow bearing are installed inside the steel frame of an active vortex purging pig. This component fully utilizes the pressure difference across the active vortex purging pig to generate torque through the impeller, thereby driving the front-end branched combined jet pipe to rotate actively. This technology forms a vortex jet at the front end of the active vortex purging pig, achieving powerful purging. It can also be used for the uniform spraying of coatings inside natural gas pipelines. This invention is specifically designed for large-diameter natural gas pipelines, ensuring reliable and stable pigging operations and preventing safety accidents. Attached Figure Description

[0079] Figure 1 This is a cross-sectional view of the active vortex purging pig in this invention;

[0080] The components are: 1. Traction ring; 2. End cap; 3. Jet pipe; 31. Drain pipe; 32. Swirl pipe; 4. Cup assembly; 5. Inner cylinder; 6. Outer cylinder; 7. Impeller. Detailed Implementation

[0081] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "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 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. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," etc., do not indicate a quantity limitation, but rather indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of 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. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more. For example, multiple positioning posts refer to two or more positioning posts. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0082] The present invention will now be described in detail.

[0083] like Figure 1 The diagram illustrates a design method for an active vortex purging pig for natural gas pipelines. The active vortex purging pig includes an outer cylinder 6, a central shaft coaxially arranged within and around the outer cylinder 6, several sets of jet pipes 3 connected to and positioned at one end of the central shaft, an impeller 7 mounted on the outside of the central shaft, and a cup assembly 4 mounted on the outer cylinder 6. The ends of the jet pipes 3 furthest from the central shaft face the natural gas pipeline used for natural gas transportation. The central shaft is rotatably coupled to the outer cylinder 6. Several sets of vent holes communicating with the interior of the central shaft are provided on the central shaft. The vent holes are located near the jets on the impeller 7 assembly. One side of pipe 3; the central shaft includes an inner cylinder 5 coaxially arranged with the outer cylinder 6 and an end cap 2 located on the side of the inner cylinder 5 away from the impeller 7. The jet pipe 3 is installed on the end cap 2, and multiple sets of vent holes are located on the inner cylinder 5. A bearing is fitted on the outer side of the inner cylinder 5 to achieve rotational cooperation with the outer cylinder 6 through the bearing. A traction ring 1 is also provided on the end cap 2. The cup assembly 4 includes a guide cup, a spacer cup, and a sealing cup. The guide cup, spacer cup, and sealing cup are all made of polyurethane, which can seal the gap between the outer wall of the outer cylinder 6 and the inner wall of the natural gas pipeline and be pushed by the natural gas, so that the pig body is pushed forward along the natural gas transportation direction.

[0084] The jet pipe 3 includes a guide pipe 31 whose axis is parallel to the axis of the inner cylinder 5 and is installed on the end cap 2, and a swirl pipe 32 connected to the end of the guide pipe 31 away from the inner cylinder 5 and whose outlet faces the inner wall of the natural gas pipeline; the guide pipe 31 is connected to the inner cylinder 4.

[0085] The impeller 7 is driven by the natural gas thrust, which drives the inner cylinder 5 to rotate. Under the combined action of the rotation of the inner cylinder 5 and the jet pipe 3, the natural gas flow inside it will generate a swirling jet gas in the jet pipe 3, which powerfully blows away the impurities in front. This improves the jet blowing effect and the ability to carry dust and droplets, and avoids the accumulation of impurities that cause the pig to get stuck in the natural gas pipeline, thus reducing the efficiency of natural gas pipeline transportation.

[0086] The jet tube 3 is hollow inside, and the outlet of the jet tube 3 is inclined to the inner wall of the natural gas pipeline, which can blow the output gas to the inner wall of the natural gas pipeline; through the pressure difference before and after and the action of the impeller 7, the jet tube 3 rotates to generate swirling jet gas, which can blow the output gas to the inner wall of the natural gas pipeline, enhancing the cleaning effect on the pipeline wall.

[0087] The waist-shaped orifice is used to guide natural gas through the impeller 7 into the inner cylinder 5, and through the jet pipe 3, form a swirling jet of gas to blow away dirt and impurities on the inner wall and in front of the natural gas pipeline, thereby achieving the effect of cleaning the pipeline.

[0088] Specifically, the following steps are included:

[0089] Step S1: The pressure difference between the front and rear ends of the outer cylinder 6 generates an active rotational torque through the impeller 7, which drives the central shaft coaxially connected to the impeller 7 to rotate; a jet pipe 3 connected to the inside of the central shaft is installed at the output end of the central shaft.

[0090] Step S2: Several waist-shaped holes are set on the central shaft to guide the natural gas passing through the impeller 7 into the central shaft and form a gas flow channel through the jet pipe 3;

[0091] Step S3: The central shaft drives the front branch assembly of the jet tube 3 to rotate, forming a swirling jet that powerfully blows the tube wall and uses the swirling effect to drive dust and even accumulated liquid forward.

[0092] Step S4: Determine the number of jet tubes 3 and the tilt angle of jet tubes 3 relative to the central axis;

[0093] Step S5: Calculate the bypass area of ​​jet tube 3;

[0094] Step S6: Calculate the bypass rate and operating speed of the active cyclone purging pig;

[0095] Step S7: Calculate the minimum standard-condition natural gas pipeline throughput required given the operating speed of the active vortex purging pig.

[0096] This invention transforms the conventional axial jet into an active rotating jet, introducing a vortex effect on top of the axial jet, which greatly improves the jet cleaning effect, achieving more thorough cleaning of natural gas pipelines and thus improving pipeline cleaning efficiency; it significantly enhances the jet purging effect and the ability to carry dust and droplets, while effectively preventing the accumulation of impurities and liquid at the bottom of the pipeline cleaner, thereby avoiding pipeline cleaner blockage; it reduces the risk of pipeline cleaning operations and ensures the safe operation of pipeline cleaning operations.

[0097] This invention uses bypass rate algorithms, jet pig operating speed calculation algorithms, and required gas delivery volume calculation algorithms to calculate and predict the basic operating conditions required for jet pig operation.

[0098] In some possible implementations, the calculation formula for the active rotational torque generated by the impeller 7 in step S1 is shown in equation (1):

[0099] T=ρQ(R2V 2t -R1V 1t (1);

[0100] Where T is the torque of impeller 7;

[0101] Q represents the flow rate through impeller 7; R1 and R2 are the radii of the inner and outer rings of impeller 7, respectively.

[0102] V 1t This represents the tangential component of the absolute velocity of the fluid flowing into the interior of the impeller 7 from the inner ring of the impeller 7.

[0103] V 2t This represents the tangential component of the absolute velocity of the fluid flowing into the impeller 7 from its outer ring.

[0104] The impeller 7 is driven by the thrust generated by the pressure difference of natural gas, which generates an active rotational torque and drives the central shaft to rotate. The flowing natural gas gas flow is ejected from the actively rotating combined jet pipe 3 to form an active vortex. The vortex effect drives dust and even accumulated liquid forward, which greatly improves the cleaning effect.

[0105] In some possible implementations, the pressure difference between the front and rear ends of the outer cylinder 6 in step S1 is calculated as follows:

[0106] P=ρgH (2);

[0107]

[0108] P = Tω (4);

[0109] Where H is the capacity obtained by a unit mass of fluid passing through impeller 7;

[0110] g is the acceleration due to gravity;

[0111] P represents the pressure difference across the active vortex purging pig.

[0112] In some possible implementations, step S4 specifically refers to:

[0113] First, the number of jet tubes 3 is initially determined. Then, 3D modeling software is used to establish the outlet flow domain space of jet tubes 3 at different inclination angles. Flow field simulation is performed using flow field calculation software. Based on the simulation results, the swirling purging intensity and purging range at different inclination angles are analyzed. Combined with the processing requirements of jet tubes 3, the tilt angle of jet tubes 3 relative to the central axis is finally determined.

[0114] Then, the number of jet tubes 3 was changed; the flow field analysis was performed again, and the number of jet tubes 3 was determined by analyzing the swirling purging intensity and purging range under different numbers of nozzles.

[0115] The final tilt angle and number of jet tubes 3 are obtained.

[0116] In some possible implementations, step S5 specifically refers to:

[0117] Step S51: Calculation of the maximum bypass area of ​​jet tube 3:

[0118]

[0119] Among them, A hmax This represents the maximum bypass area of ​​jet tube 3;

[0120] A is the internal cross-sectional area of ​​the natural gas pipeline;

[0121] F f The frictional force between the diaphragm assembly 4 and the inner wall of the natural gas pipeline during operation;

[0122] m is the mass of the active vortex purging pig;

[0123] P1 is the pressure at the end of the active swirling purge cleaner away from the jet tube 3;

[0124] P3 is the pressure at the end of the active swirling purge cleaner near the jet tube 3.

[0125] Step S52: Calculation of minimum bypass area for jet tube 3;

[0126]

[0127] Among them, A hmin K represents the minimum bypass area of ​​jet tube 3. p ρ is the pressure loss coefficient of natural gas flowing through the jet orifice of the active swirl purge pig; Q2 is the natural gas density; T2 is the natural gas flow rate; T is the gas temperature before throttling; c P is the critical temperature. cP is the critical pressure. r For comparison of pressure; T r For comparison temperature; c p The specific heat of natural gas; f(P) r ,T r The calculation is as follows:

[0128]

[0129] In some possible implementations, the bypass rate of the active swirl purge cleaner is calculated in step S6, specifically by calculating the total area of ​​all jet tubes 3 perforations using formula (8).

[0130]

[0131] in,

[0132] K p This is the kinetic energy correction factor, an empirical constant;

[0133] ρ h The density of natural gas under operating conditions;

[0134] Q represents the operating natural gas flow rate;

[0135] A h This represents the total area of ​​the injection holes on the jet nozzle.

[0136] Active vortex purging pig bypass rate The calculation is as follows:

[0137]

[0138] In some possible implementations, the frictional force F between the cup assembly 4 and the inner wall of the natural gas pipeline during operation f Calculated as;

[0139] F f =2πr p L p μ f N f (10);

[0140] Where, r p The inner radius of the pipe;

[0141] L p The contact length between the cup assembly and the pipe;

[0142] μ f The coefficient of friction of the leather cup;

[0143] The clamping force between the diaphragm cup and the natural gas pipeline in the diaphragm cup assembly 4 is calculated by equation (11);

[0144]

[0145] Where E is the elastic modulus of the diaphragm; δ p For the interference fit of the leather cup; γ i Poisson's ratio for leather bowls;

[0146] In equation (8), the kinetic energy correction coefficient K is calculated from equation (12);

[0147]

[0148] In the formula d h The diameter of the jet tube's three orifices.

[0149] In some possible implementations, the operating speed V of the active cyclone purging pig in step S6 is... pig Performing calculations specifically refers to:

[0150]

[0151] In the formula,

[0152] V g —Natural gas flow velocity;

[0153] φ——Bypass rate of active vortex purging pig, (0~1);

[0154] α — Inclination angle of the natural gas pipeline;

[0155] ρ bp —Natural gas density under operating conditions;

[0156] In some possible implementations, step S7 specifically refers to:

[0157] Set the active swirl purging pig speed, assume the most extreme working condition, the natural gas pipeline inclination angle is 90° uphill, calculate the natural gas compressibility factor Z under a given pressure, calculate the natural gas density under the working condition, and calculate the natural gas working speed V using formula (13). g ;

[0158] Calculate the minimum standard-condition natural gas pipeline throughput Q0 required given a fixed operating speed of the active vortex purging pig;

[0159]

[0160] Where T0 is the standard temperature and P0 is the standard pressure.

[0161] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A design method for an active vortex purging pig for natural gas pipelines, characterized in that, The active cyclone purging pipe cleaner includes an outer cylinder, a central shaft coaxially arranged inside and with the outer cylinder, several sets of jet tubes disposed at one end of the central shaft and communicating with the central shaft, an impeller disposed outside the central shaft, and a cup assembly disposed on the outer cylinder; the end of the jet tube away from the central shaft faces the natural gas pipeline used for natural gas transportation; the central shaft is rotatably engaged with the outer cylinder; several sets of vent holes communicating with the interior of the central shaft are provided on the central shaft; the vent holes are located on the side of the impeller assembly near the jet tubes; specifically, it includes the following steps: Step S1: Utilize the pressure difference between the front and rear ends of the outer cylinder to generate an active rotational torque through the impeller, driving the central shaft, which is coaxially connected to the impeller, to rotate; install a jet pipe, which is connected to the interior of the central shaft, at the output end of the central shaft; Step S2: Several waist-shaped holes are set on the central shaft to guide the natural gas passing through the impeller into the central shaft and form a gas flow channel through the jet pipe; Step S3: The central shaft drives the front branch assembly of the jet tube to rotate, forming a swirling jet that powerfully blows the tube wall and uses the swirling effect to drive dust and even accumulated liquid forward. Step S4: Determine the number of jet tubes and the tilt angle of the jet tubes relative to the central axis; Step S5: Calculate the bypass area of ​​the jet tube; Step S6: Calculate the bypass rate and operating speed of the active cyclone purging pig; Step S7: Calculate the minimum standard-condition natural gas pipeline throughput required given the operating speed of the active vortex purging pig.

2. The design method of an active vortex purging pig for natural gas pipelines according to claim 1, characterized in that, The formula for calculating the active rotational torque generated by the impeller in step S1 is shown in equation (1): T=ρQ(R2V 2t -R1V 1t ) (1); Where T is the impeller torque; Q represents the flow rate through the impeller; R1 and R2 are the radii of the inner and outer rings of the impeller, respectively. V 1t This represents the tangential component of the absolute velocity of the fluid flowing into the impeller from the inner ring of the impeller. V 2t This represents the tangential component of the absolute velocity of the fluid flowing into the impeller on the outer ring of the impeller.

3. The design method of an active vortex purging pig for natural gas pipelines according to claim 2, characterized in that, The pressure difference between the front and rear ends of the outer cylinder in step S1 is calculated as follows: P=ρgH (2); P = Tω (4); Where H is the capacity obtained by a unit mass of fluid passing through the impeller; g is the acceleration due to gravity; P represents the pressure difference across the active vortex purging pig.

4. The design method of an active vortex purging pig for natural gas pipelines according to claim 3, characterized in that, Step S4 specifically refers to: First, the number of jet tubes is initially determined. Then, 3D modeling software is used to establish the flow domain space of the jet tube outlet at different inclination angles. Flow field simulation is performed using flow field calculation software. Based on the simulation results, the swirling purging intensity and purging range at different inclination angles are analyzed. Finally, the inclination angle of the jet tube relative to the central axis is determined in combination with the processing requirements of the jet tube. Then, change the number of jet tubes; The flow field analysis was performed again, and the number of jet tubes was determined by analyzing the swirling purging intensity and purging range under different numbers of nozzles. The final tilt angle and number of jet tubes are obtained.

5. The design method of an active vortex purging pig for natural gas pipelines according to claim 4, characterized in that, Step S5 specifically refers to: Step S51: Calculation of the maximum bypass area of ​​the jet tube: Among them, A hmax This represents the maximum bypass area of ​​the jet tube; A is the internal cross-sectional area of ​​the natural gas pipeline; F f The frictional force between the diaphragm cup and the inner wall of the natural gas pipeline during operation; m is the mass of the active vortex purging pig; P1 is the pressure at the end of the active swirling purge cleaner furthest from the jet tube; P3 is the pressure at the end of the active vortex purging cleaner near the jet tube. Step S52: Calculation of minimum bypass area of ​​jet tube; Among them, A hmin K represents the minimum bypass area of ​​the jet tube. p ρ is the pressure loss coefficient of natural gas flowing through the jet orifice of the active swirl purge pig; Q2 is the natural gas density; T2 is the natural gas flow rate; T is the gas temperature before throttling; c P is the critical temperature. c P is the critical pressure. r For comparison of pressure; T r For comparison temperature; c p The specific heat of natural gas; f(P) r ,T r The calculation is as follows: f(P r ,T r )=2.343T r -2.04 -0.071P r +0.0568 (7)。 6. The design method of an active vortex purging pig for natural gas pipelines according to claim 5, characterized in that, In step S6, the bypass rate of the active vortex purging cleaner is calculated, specifically by calculating the total area of ​​all jet tube perforations using formula (8). in, K p This is the kinetic energy correction factor, an empirical constant; ρ h The density of natural gas under operating conditions; Q represents the operating natural gas flow rate; A h This represents the total area of ​​the injection holes on the jet nozzle. Active vortex purging pig bypass rate The calculation is as follows:

7. The design method of an active vortex purging pig for natural gas pipelines according to claim 6, characterized in that, During operation, the frictional force F between the diaphragm cup and the inner wall of the natural gas pipeline in the diaphragm cup assembly... f Calculated as; F f =2πr p L p m f N f (10); Where, r p The inner radius of the pipe; L p The contact length between the cup assembly and the pipe; μ f The coefficient of friction of the leather cup; The clamping force between the diaphragm and the natural gas pipeline in the diaphragm assembly is calculated by equation (11); Where E is the elastic modulus of the cup; δ p For the interference fit of the leather cup; γ i Poisson's ratio for leather bowls; In equation (8), the kinetic energy correction coefficient K is calculated from equation (12); In the formula d h The diameter of the jet nozzle is denoted as .

8. The design method of an active vortex purging pig for natural gas pipelines according to claim 7, characterized in that, In step S6, the operating speed V of the active cyclone purging pig is... pig Performing calculations specifically refers to: In the formula, V g —Natural gas flow velocity; φ——Bypass rate of active vortex purging pig, (0~1); α — Inclination angle of the natural gas pipeline; ρ bp —Natural gas density under operating conditions.

9. The design method of an active vortex purging pig for natural gas pipelines according to claim 8, characterized in that, Step S7 specifically refers to: Set the active swirl purging pig speed, assume the most extreme working condition, the natural gas pipeline inclination angle is 90° uphill, calculate the natural gas compressibility factor Z under a given pressure, calculate the natural gas density under the working condition, and calculate the natural gas working speed V using formula (13). g ; Calculate the minimum standard-condition natural gas pipeline throughput Q0 required given a fixed operating speed of the active vortex purging pig; Where T0 is the standard temperature and P0 is the standard pressure.

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