A device and method for intelligent control of natural gas compression and mixed gas lifting based on servo direct drive

Abstract

The application relates to a device and a method for intelligent control natural gas compression mixed lifting based on a servo direct drive, which comprises a compression cylinder, the inside of the compression cylinder being provided with a compression piston for reciprocating linear motion; a servo direct drive unit, which comprises a servo electric cylinder and a servo control system connected in an electric manner, wherein the servo electric cylinder is in driving connection with the compression piston; wherein the servo control system is configured to: in each compression stroke of the compression piston, based on real-time acquired compression working condition parameters, calculate and generate a piston speed control curve suitable for the compression stroke, and control the servo electric cylinder to drive the compression piston to operate according to a non-uniform speed motion law defined by the piston speed control curve. The device can directly solve the inherent impact vibration problem of a traditional compressor, and comprehensively improve the comprehensive performance of the equipment in the aspects of efficiency, reliability and intelligence.

Description

Technical Field

[0001] This invention belongs to the technical field of natural gas extraction and gathering equipment, specifically relating to a device and method for intelligent control of natural gas compression and mixed transmission gas lift based on servo direct drive. Background Technology

[0002] During the extraction and gathering of natural gas, as the well pressure naturally decreases, it is necessary to pressurize the natural gas at the wellhead to a pressure that meets the requirements of pipeline transportation through booster equipment. Reciprocating piston compressors, due to their high pressure ratio and strong adaptability, are widely used in well site pressurization and gas gathering stations. Currently, mainstream reciprocating compressors are typically powered by an electric motor or internal combustion engine, which converts the rotary motion into the reciprocating linear motion of the piston within the cylinder through a crank-connecting rod mechanism, thus periodically completing the intake, compression, and discharge of gas.

[0003] In the working cycle of a reciprocating piston compressor, the "compression stroke" specifically refers to the physical process by which the piston pressurizes the gas enclosed within the cylinder. The beginning of this stroke is called "bottom dead center," where the piston moves closest to the bottom of the cylinder (crankshaft side). At this point, the cylinder volume is at its maximum, the intake valve is closed, and the cylinder contains the largest volume of gas to be compressed. The end of the stroke is called "top dead center," where the piston moves furthest from the bottom of the cylinder. At this point, the cylinder volume is at its minimum, the gas is compressed to its highest pressure, and the exhaust valve opens.

[0004] It is precisely at these two crucial points that the shortcomings of traditional mechanical structures are fully exposed: due to the rigid kinematic constraints of the crankshaft and connecting rod, the piston must instantly accelerate from a state of zero velocity at bottom dead center, and instantly decelerate to zero and immediately reverse direction at top dead center. This instantaneous and dramatic change in velocity "from zero to zero" and "from zero to zero" at the start and end points directly leads to extremely large acceleration peaks, thereby inducing periodic and unavoidable rigid impact forces on the machine components. This is the most fundamental physical cause of equipment vibration, wear, and fatigue damage. This problem severely restricts the operational reliability and service life of equipment in long-term, unattended well site environments, and is a core technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a device and method for intelligent control of natural gas compression and blending gas lift based on servo direct drive. The technical problem to be solved by this invention is achieved through the following technical solution: This invention provides a device and method for intelligent control of natural gas compression and blending gas lift based on servo direct drive. The device includes: A compression cylinder, which has a compression piston inside for reciprocating linear motion; A servo direct drive unit includes an electrically connected servo cylinder and a servo control system, wherein the servo cylinder is drivenly connected to the compression piston; The servo control system is configured to: in each compression stroke of the compression piston, calculate and generate a piston speed control curve suitable for that compression stroke based on real-time acquired compression condition parameters, and control the servo electric cylinder to drive the compression piston to run according to the non-uniform motion law defined by the piston speed control curve.

[0006] Compared with the prior art, the beneficial effects of the present invention are as follows: To address the problem of existing natural gas compression mechanisms easily causing periodic and unavoidable rigid impacts, which reduce equipment reliability and service life, this invention provides a device and method for intelligent control of natural gas compression and mixed-transport gas lift based on servo direct drive. This device completely eliminates the crank-connecting rod mechanism by employing a servo electric cylinder that directly drives the piston through a rigid direct connecting rod. This feature eliminates transmission errors and delays caused by motion conversion and gaps at multiple hinge points, ensuring that the driving force is transmitted directly along the axial direction without loss or lag, providing a rigid and simple mechanical foundation for high-precision motion control and reducing vibration sources at the source. Secondly, the servo control system can dynamically calculate and generate an optimized curve based on real-time operating parameters, causing the compression piston to operate according to a non-uniform "slow-fast-slow" speed pattern, thereby eliminating mechanical impacts and vibrations at the start and end points of the stroke. Furthermore, the device adopts a highly integrated modular skid-mounted design, significantly improving overall operational stability, reliability, energy efficiency, and intelligence. In summary, this application directly solves the inherent impact and vibration problems of traditional compressors and comprehensively improves the overall performance of the equipment in terms of efficiency, reliability, and intelligence. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the structure of a servo direct drive-based intelligent control device for natural gas compression and blending gas lift according to an embodiment of the present invention. Figure 2 This is a flowchart of a method for intelligent control of natural gas compression and blending gas lift based on servo direct drive, provided by an embodiment of the present invention.

[0008] Explanation of icon numbers: 1-Compression cylinder; 2-Compression piston; 3-Servo electric cylinder; 4-Servo control system; 5-Intake pipe; 6-Exhaust pipe; 7-Rigid connector; 9-Skirt base; 51-First working condition monitoring sensor; 52-Second working condition monitoring sensor. Detailed Implementation

[0009] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0010] In the description of this invention, 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 indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0011] 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 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. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0012] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, disclosure, and appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0013] The present invention will now be described in detail with reference to the accompanying drawings, which describes an intelligent control device and method for natural gas compression and blending gas lift based on servo direct drive.

[0014] Figure 1 This is a schematic diagram of a servo-driven intelligent control device for natural gas compression and blending gas lift, provided in an embodiment of the present invention. Figure 1 As shown, the device includes: a compression cylinder 1, which has a compression piston 2 inside for reciprocating linear motion; a servo direct drive unit, including a servo cylinder 3 and a servo control system 4 electrically connected, wherein the servo cylinder 3 is drivenly connected to the compression piston 2; wherein the servo control system 4 is configured to: in each compression stroke of the compression piston 2, calculate and generate a piston speed control curve suitable for the compression stroke based on real-time acquired compression condition parameters, and control the servo cylinder 3 to drive the compression piston 2 to run according to the non-uniform motion law defined by the piston speed control curve.

[0015] This also includes: a rigid connector 7; the servo electric cylinder 3 is driven to the compression piston 2 via the rigid connector 7. The rigid connector 7 is a straight connecting rod.

[0016] Traditional crank-connecting rod mechanisms are "rotational-linear" motion conversion mechanisms. Their long transmission chains and multiple kinematic pairs (such as crankshaft bearings and connecting rod big-end and small-end bearings) inevitably lead to clearance, friction, and elastic deformation. In contrast, this invention eliminates the complex crankcase, crankshaft, and connecting rod (with bearings), replacing them with a simple straight connecting rod. This results in an exceptionally simple mechanical structure for the entire drive-compression unit, significantly reducing the number of parts, effectively minimizing potential failure points, and ensuring that the driving force is transmitted to the piston with almost no lag or attenuation. This allows the piston to closely follow the commands of the control system. The absence of buffering and lag caused by flexible or articulated joints allows the precise "slow-fast-slow" curve to be faithfully executed at the physical level.

[0017] Please continue to refer to Figure 1 The device also includes an intake pipe 5 and an exhaust pipe 6. The intake pipe 5 and the exhaust pipe 6 are respectively connected to the cylinder body of the compression cylinder 1 and communicate with the internal cavity of the compression cylinder 1 to cooperate with the reciprocating linear motion of the compression piston 2 to realize the intake and exhaust of natural gas. Furthermore, the intake pipe 5 is equipped with a first operating condition monitoring sensor 51 for real-time monitoring of intake operating condition parameters, and the exhaust pipe 6 is equipped with a second operating condition monitoring sensor 61 for real-time monitoring of exhaust operating condition parameters. Both the first operating condition monitoring sensor 51 and the second operating condition monitoring sensor 61 are connected to the servo control system 4 to provide compression operating condition parameters.

[0018] It should be noted that the first operating condition monitoring sensor 51 and the second operating condition monitoring sensor 61 can be selected from conventional and mature sensor devices in the field according to actual monitoring needs. Specifically: the first operating condition monitoring sensor 51 can be a combination of a pressure transmitter, a temperature sensor, a flow meter, an online gas chromatograph, a mass spectrometer, or a densitometer; the second operating condition monitoring sensor 61 can be a combination of a pressure transmitter and a temperature sensor.

[0019] Please continue to refer to Figure 1 An intake valve 52 is installed on the intake pipe 5, and an exhaust valve 62 is installed on the exhaust pipe 6.

[0020] Here, the intake operating parameters include at least one of intake pressure, intake temperature, intake flow rate, and gas composition; the exhaust operating parameters include at least one of exhaust pressure and exhaust temperature; and the compression operating parameters include a dataset consisting of one or more of the following: intake operating parameters, exhaust operating parameters, target exhaust pressure, real-time compression ratio, and cylinder pressure change rate.

[0021] For example, gas composition is a comprehensive dataset used to characterize the chemical and physical composition of the intake medium. It primarily contains the following quantifiable or identifiable information: 1) Liquid component content: This is the most direct and key indicator for judging the "gas-liquid mixed transport state". Specifically, it refers to the mass percentage or volume percentage of liquid hydrocarbons (such as condensate oil) and / or free water in the intake air. When this content exceeds the set safety threshold, it is judged as a gas-liquid two-phase flow condition.

[0022] 2) Hydrocarbon gas composition: This refers to the mole fraction or volume fraction of each component in natural gas, such as methane, ethane, propane, and butane. This information helps in calculating the gas's average molecular weight, compressibility factor, and specific heat capacity, and is fundamental for accurately calculating compression kinetics and thermodynamic processes.

[0023] 3) Non-hydrocarbon components: including but not limited to the content of carbon dioxide, hydrogen sulfide, nitrogen, etc. These components affect the corrosiveness, thermal properties, and safety requirements of the gas, and are also necessary inputs for achieving precise compression control.

[0024] 4) Key physical property parameters: Parameters that can be calculated in real time based on the above component analysis or obtained directly through associated sensors, such as gas density, relative molecular mass, adiabatic index, etc.

[0025] Here, the real-time compression ratio refers to the ratio of the target pressure of the gas compressed in the cylinder during the current compression stroke (usually a preset target exhaust pressure or a pressure value set in real time according to pipeline conditions) to the real-time absolute pressure of the gas intake in the cylinder at the beginning of the compression stroke (bottom dead center). It can be obtained by dividing the target exhaust pressure by the real-time intake pressure.

[0026] Furthermore, the cylinder pressure change rate (i.e., the rate of change of cylinder gas pressure over time, dP / dt) can be obtained by installing a high dynamic response pressure sensor on the cylinder wall or cylinder head of the compression cylinder 1, or by using the known real-time piston motion parameters (obtained through the encoder feedback of the servo electric cylinder 3) and parameters such as real-time intake pressure and gas composition of the servo control system 4, combined with the geometric model of the cylinder working volume and the thermodynamic equation of state of the gas (such as a model considering real-time gas composition correction), to calculate or deduce the theoretical pressure value and its change rate in the cylinder in real time.

[0027] Here, the piston speed control curve is configured to include three speed control stages connected in sequence: 1. Initial acceleration phase: (e.g., within the first 10%-30% of the compression stroke) Control the compression piston 2 to accelerate from a stationary or low-speed state to the first speed from the beginning of the compression stroke; 2. Mid-stage operation: (e.g., in the subsequent 40%-80% range) Control the compression piston 2 to run at a constant speed of a second speed higher than the first speed or continue to accelerate; 3. End of deceleration phase: Before the compression piston 2 reaches the top dead center, control the compression piston 2 to decelerate to a third speed that is less than or equal to the first speed, and reach the top dead center at the third speed.

[0028] It should be noted that the percentages in the examples above can be adjusted according to actual needs.

[0029] It should be noted that the piston speed control curve is obtained by optimizing an existing curve model using compression condition parameters. Specifically, in order to achieve efficient and reliable real-time control, the servo control system 4 has a pre-stored basic curve model library. This library contains a variety of pre-designed standard piston speed control curves for different typical operating conditions (such as different intake pressure ranges, target compression ratios, or gas composition characteristics) as a benchmark for optimization calculations.

[0030] Once the system collects compression parameters in real time, its curve generation mechanism includes the following two core steps: 1. Selection of Curves The system first matches the key parameters acquired in real time (such as the real-time compression ratio determined by the intake pressure and the target exhaust pressure) with the operating condition labels corresponding to each curve in the basic curve model library. Through comparison, it quickly selects one or more basic curves that best match the current operating condition, serving as the initial reference for subsequent optimization. This ensures that the optimization calculations start from a reasonable starting point, improving computational efficiency and reliability.

[0031] 2. Curve optimization methods After selecting a baseline curve, the system does not use it directly, but instead enters a real-time optimization calculation process. The core of this process is to dynamically correct the key parameters of the selected baseline curve using real-time, more comprehensive compression parameters (such as precise inlet temperature, gas composition, or instantaneous pressure change rate) through interpolation algorithms, parameterized adjustments, or online optimization algorithms based on physical models.

[0032] For example, the system uses interpolation calculations based on the difference between the real-time intake pressure and the corresponding pressure in the gas chamber curve to redetermine the rate of change of speed and the transition point position in each stage of the compression stroke (especially the acceleration and deceleration stages); or it adjusts the duration of the mid-range high-speed operation stage according to the gas composition to adapt to the compressibility of the gas. The final result is a completely new piston speed control curve that inherits the advantages of the basic curve structure but whose parameters are precisely calibrated through real-time data.

[0033] It should be noted that the servo control system 4 is also configured to execute an anti-liquid slugging control strategy when the gas composition in the compression condition parameters indicates that the intake is in a gas-liquid mixed transport state. The anti-liquid slugging control strategy includes reducing the acceleration during the initial acceleration phase and / or increasing the piston stroke displacement corresponding to the initial acceleration phase.

[0034] The reason for adopting the combination optimization of "reducing the initial acceleration" and "increasing the initial displacement" when implementing the anti-liquid slamming control strategy is that there are essential differences in physical properties between the gas-liquid two-phase medium and the pure gas phase medium during the compression process. The core is to avoid the extremely harmful phenomenon of "liquid slamming".

[0035] Here, the servo control system 4 is also configured to: during the return stroke phase after the exhaust valve of the compression piston 2 is closed, control the servo electric cylinder 3 to operate in generator mode to recover the energy of the expansion of the remaining gas in the cylinder, thereby effectively improving the system energy efficiency.

[0036] Please continue to refer to Figure 1 The compressor cylinder 1, servo direct drive unit and auxiliary machine are integrated on the skid base 8 to form a compact modular booster unit; the auxiliary machine includes one or more of the following: cooler, gas-liquid separator, lubrication system and power distribution unit.

[0037] Corresponding to the above-mentioned device for intelligent control of natural gas compression and blending gas lift based on servo direct drive, this embodiment of the invention also provides a method for intelligent control of natural gas compression and blending gas lift based on servo direct drive. Figure 2 This is a flowchart illustrating a method for intelligent control of natural gas compression and blending gas lift based on servo direct drive, as provided in an embodiment of the present invention. Figure 2 As shown, this method is applied to the aforementioned intelligent control gas compression and blending lift device based on servo direct drive; specifically, it includes: S1: Real-time acquisition of compression operating parameters; S2: Based on compression parameters, calculate and generate a piston speed control curve for the current compression stroke in real time; S3: According to the piston speed control curve, control the servo electric cylinder 3 to drive the compression piston 2 to perform reciprocating linear motion inside the compression cylinder 1 according to the non-uniform motion law defined by the piston speed control curve.

[0038] To address the problem of existing natural gas compression mechanisms easily causing periodic, unavoidable rigid impacts, which reduce equipment reliability and service life, this invention provides a device and method for intelligent control of natural gas compression and mixed-transport gas lift based on servo direct drive. This device completely eliminates the crank-connecting rod mechanism by employing a servo electric cylinder that directly drives the piston through a rigid direct connecting rod. This feature eliminates transmission errors and delays caused by motion conversion and gaps at multiple hinge points, ensuring lossless and lag-free direct transmission of driving force along the axial direction. This provides a rigid and simple mechanical foundation for high-precision motion control, reducing vibration sources at the source. Secondly, the servo control system can dynamically calculate and generate an optimized curve based on real-time operating parameters, causing the compression piston to operate according to a non-uniform "slow-fast-slow" speed pattern, thereby eliminating mechanical impacts and vibrations at the start and end points of the stroke. Furthermore, the device adopts a highly integrated modular skid-mounted design, significantly improving overall operational stability, reliability, energy efficiency, and intelligence. In summary, this application solves the inherent impact and vibration problems of traditional compressors and comprehensively improves the overall performance of the equipment in terms of efficiency, reliability, and intelligence.

[0039] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A device for intelligent control of natural gas compression and blending gas lift based on servo direct drive, characterized in that, include: A compression cylinder (1) is provided inside which a compression piston (2) is used to perform reciprocating linear motion; The servo direct drive unit includes an electrically connected servo cylinder (3) and a servo control system (4), wherein the servo cylinder (3) is drivenly connected to the compression piston (2); The servo control system (4) is configured to: in each compression stroke of the compression piston (2), calculate and generate a piston speed control curve suitable for the compression stroke based on the real-time acquired compression condition parameters, and control the servo electric cylinder (3) to drive the compression piston (2) to run according to the non-uniform motion law defined by the piston speed control curve; The system also includes an intake pipe (5) and an exhaust pipe (6); and the intake pipe (5) is equipped with a first condition monitoring sensor (51) for real-time monitoring of intake operating parameters, and the exhaust pipe (6) is equipped with a second condition monitoring sensor (61) for real-time monitoring of exhaust operating parameters. Both the first condition monitoring sensor (51) and the second condition monitoring sensor (61) are connected to the servo control system (4) for providing the compression operating parameters. The intake operating parameters include at least one of intake pressure, intake temperature, intake flow rate, and gas composition; The exhaust operating parameters include at least one of exhaust pressure and exhaust temperature; The compression condition parameters include a dataset composed of multiple parameters such as the intake condition parameters, the exhaust condition parameters, the target exhaust pressure, the real-time compression ratio, and the rate of change of cylinder pressure.

2. The device for intelligent control of natural gas compression and blending gas lift based on servo direct drive according to claim 1, characterized in that, The intake pipe (5) and the exhaust pipe (6) are respectively connected to the cylinder body of the compression cylinder (1) and communicate with the internal cavity of the compression cylinder (1) to cooperate with the reciprocating linear motion of the compression piston (2) to realize the intake and discharge of natural gas.

3. The device for intelligent control of natural gas compression and blending gas lift based on servo direct drive according to claim 1, characterized in that, The piston speed control curve is configured to include three speed control stages connected in sequence: 1) Initial acceleration phase: Control the compression piston (2) to accelerate from a stationary or low-speed state to a first speed from the beginning of the compression stroke; 2) Mid-stage operation: Control the compression piston (2) to run at a constant speed higher than the first speed or continue to accelerate; 3) End of deceleration phase: Before the compression piston (2) reaches the top dead center, control the compression piston (2) to decelerate to a third speed less than or equal to the first speed, and reach the top dead center at the third speed.

4. The device for intelligent control of natural gas compression and blending gas lift based on servo direct drive according to claim 3, characterized in that, The servo control system (4) is also configured to: When the gas composition in the compression condition parameters indicates that the intake air is in a gas-liquid mixed transport state, an anti-liquid slugging control strategy is executed. The anti-liquid slugging control strategy includes reducing the acceleration during the initial acceleration phase and / or increasing the piston stroke displacement corresponding to the initial acceleration phase.

5. The device for intelligent control of natural gas compression and blending gas lift based on servo direct drive according to claim 1, characterized in that, The servo control system (4) is also configured to: During the return stroke phase after the exhaust valve of the compression piston (2) is closed, the servo electric cylinder (3) is controlled to operate in generator mode to recover the energy of the expansion of the remaining gas in the cylinder.

6. The device for intelligent control of natural gas compression and blending gas lift based on servo direct drive according to claim 1, characterized in that, Also includes: Rigid connector (7); the servo electric cylinder (3) is driven to the compression piston (2) through the rigid connector (7).

7. The device for intelligent control of natural gas compression and blending gas lift based on servo direct drive according to claim 6, characterized in that, The rigid connector (7) is a straight connecting rod.

8. The device for intelligent control of natural gas compression and blending gas lift based on servo direct drive according to claim 1, characterized in that, The compression cylinder (1), the servo direct drive unit and the auxiliary machine are integrated on the skid base (8) to form a compact modular booster unit; the auxiliary machine includes one or more of the following: a cooler, a gas-liquid separator, a lubrication system and a power distribution unit.

9. A method for intelligent control of natural gas compression and blending gas lift based on servo direct drive, characterized in that, The method is used in the servo-driven intelligent control natural gas compression and mixing lift device according to any one of claims 1 to 8; the method includes: S1: Real-time acquisition of compression operating parameters; S2: Based on the compression condition parameters, calculate and generate a piston speed control curve for the current compression stroke in real time; S3: According to the piston speed control curve, control the servo electric cylinder (3) to drive the compression piston (2) to perform reciprocating linear motion inside the compression cylinder (1) according to the non-uniform motion law defined by the piston speed control curve.

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