Polymer mixing prying device control system and control method thereof

Abstract

The invention relates to a polymer mixing prying device control system and a control method thereof.The control system comprises a prying frame, and a centrifugal pump assembly, a powder tank rotor pump assembly, a mixing device and a screw feeder are integrated on the prying frame; a centrifugal pump assembly, a powder tank rotor pump assembly, a mixing device, a screw feeder and other units are integrated on the same prying frame, and the problems that traditional prying equipment is dispersed in function, large in occupied area and difficult to move are solved. All system pipelines are prefabricated and connected in a factory, only external interface butt joint needs to be completed on site, the installation and debugging period is shortened by more than 60%, and the system is particularly suitable for offshore platforms, oil fields and other scenes needing rapid deployment.

Description

Technical Field

[0001] This invention relates to the field of petroleum fracturing technology, specifically to a control system and control method for a polymer mixing skid device. Background Technology

[0002] Traditional polymer blending units often use diesel engines to drive hydraulic systems, which has the following problems: 1. The drive method is relatively outdated, mostly using diesel engines to drive hydraulic systems, which has problems such as high noise, high energy consumption, serious exhaust pollution, high maintenance costs, and the need for regular fuel replenishment. Its application is limited, especially in areas with strict environmental protection requirements or on offshore platforms. 2. Low degree of skid-mounting / poor integration: Although some units are skid-mounted, the functional units (feeding, conveying, mixing, and control) are scattered, resulting in a large footprint, complex pipeline connections, long on-site installation and commissioning cycle, and inconvenience in relocation. 3. Low level of automation and intelligence: The accuracy of dry powder dosing and the control of solution concentration mainly rely on manual experience or simple instruments, which are easily affected by human factors; 4. Low energy efficiency: Energy loss occurs in the transmission of hydraulic systems, reducing overall energy efficiency; 5. Poor operating environment: Diesel engine noise and polymer dry powder dust are detrimental to the health of operators. Summary of the Invention

[0003] To address the above problems, this invention provides a control system and control method for a polymer blending skid device that is fully electric-driven, highly skid-integrated, and intelligently controlled.

[0004] The technical solution adopted in this invention is: A control system for a polymer mixing skid device includes a skid frame, characterized in that: a centrifugal pump assembly, a powder tank rotor pump assembly, a mixing device, and a screw feeder are integrated on the skid frame; the powder outlet of the powder tank is connected to the powder inlet of the mixing device through the screw feeder; and a hydraulic motor in the hydraulic station drives the screw feeder to transport the polymer dry powder in the powder tank to the mixing device. The outlet of the centrifugal pump assembly is connected to the inlet of the mixing device. Clean water enters the centrifugal pump through the suction manifold, and after being pressurized by the centrifugal pump, it enters the mixing device. The mixing outlet of the mixing device is connected to the rotor pump assembly through a low-pressure manifold. After the dry powder and water are mixed inside the mixing device, they are discharged outward through the rotor pump assembly.

[0005] Preferably, the skid also integrates a vertical centrifugal pump assembly, which serves as a backup pump and is connected in parallel with the centrifugal pump assembly, with a valve separating them.

[0006] Preferably, a flow meter is installed at the outlet of the centrifugal pump assembly.

[0007] Preferably, a wetting funnel is provided between the screw feeder and the mixing device. The dry powder is discharged through the screw feeder and enters the wetting funnel. After being moistened, it enters the mixing device.

[0008] Preferably, the skid also integrates a liquid filling unit for adjusting the rotational speed and displacement of the rotor pump assembly.

[0009] A control method for the control system of the above-mentioned polymer blending skid device is characterized by comprising the following steps: S1. Parameter setting: Set the liquid dispensing rate, water-powder ratio, and liquid addition ratio through the human-machine interface; S2. System self-test: Collect signals from each sensor to determine whether the device meets the start-up conditions; S3. Sequential Start-up: Start the hydraulic pump, centrifugal pump assembly, mixing device and rotor pump assembly of the hydraulic station in sequence according to the preset logic; S4. Powder control: Adjust the powder feeding rate in real time based on the theoretical powder feeding rate and the feedback of the screw feeder's auger speed; S5. Liquid Addition Control: Precise closed-loop control of additive flow rate is achieved through a flow meter and a proportional valve; S6. Process Regulation: Dynamically regulate each actuator to maintain stable system pressure, flow rate and ratio; S7. Safety Protection: Automatic alarm when real-time monitoring values ​​are abnormal; S8. Operation complete: Automatically clear the cumulative amount and reset the equipment.

[0010] As a preferred option, the specific steps of S2 are as follows: collect the rotation speed, suction flow rate, discharge pressure, water quality parameters and valve status signals of the screw feeder, determine whether the system is in a safe state, and if an abnormality is detected, enter the alarm or protection mode; if the detection is normal, control the rotor pump assembly and centrifugal pump assembly to enter the working state in sequence.

[0011] As a preferred option, the specific steps of S6 are as follows: compare the actual liquid preparation parameters with the set values ​​in real time, and dynamically adjust each actuator through the PID algorithm to maintain the stability of system pressure, flow rate and ratio.

[0012] The beneficial effects of this invention are as follows: By adopting a modular skid design, the centrifugal pump assembly, powder tank rotor pump assembly, mixing device and screw feeder are integrated on the same skid, solving the problems of traditional skid-mounted equipment having dispersed functions, large footprint and difficult relocation; the pipelines of each system are prefabricated and connected in the factory, and only external interface docking needs to be completed on site, shortening the installation and commissioning cycle by more than 60%, which is especially suitable for scenarios that require rapid deployment, such as offshore platforms and oil fields.

[0013] Key power units such as the centrifugal pump assembly, rotor pump assembly, and liquid addition unit all utilize direct-drive permanent magnet variable frequency motors. These motor drives offer fast response and high control precision, enabling more accurate adjustment of equipment operating parameters. They are also smaller than traditional asynchronous motors, saving 20%–30% in energy. Through unified control of the frequency converter within the variable frequency distribution cabinet, the motor speed can be intelligently adjusted in real-time according to mixing requirements (such as different concentrations of polymer solutions or different flow rates), achieving precise control of centrifugal pump flow and rotor pump displacement. In the liquid addition unit, the permanent magnet variable frequency motor drives the cam pump via a reducer, allowing for additive dosing accuracy control within ±1%, solving the problems of lag and low precision in traditional hydraulic drive displacement adjustment. Attached Figure Description

[0014] Figure 1-2 This is a schematic diagram of the overall structure of the present invention; Figure 3 A schematic diagram of the pipe connection for mixing water and polymer powder; Figure 4 This is a system schematic diagram of the control system of the present invention; Figure 5 This is a control flowchart of the control system of the present invention; The components include: 1. Skid; 2. Variable frequency power distribution cabinet; 3. Pneumatic system; 4. Centrifugal pump assembly; 5. Powder tank; 6. Low-pressure manifold; 7. Rotary pump assembly; 8. Vertical centrifugal pump assembly; 9. Liquid addition unit; 10. Mixing device; 11. Hydraulic station; 12. Screw feeder; 13. Intelligent monitoring system; 14. Suction manifold; 15. Flow meter; 16. Wetting funnel; 17. Discharge manifold. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0016] like Figure 1-3 As shown, the present invention discloses a control system and control method for a polymer mixing skid device, comprising a skid 1, on which a frequency conversion distribution cabinet 2, an air circuit system 3, a centrifugal pump assembly 4, a powder tank 5, a low-pressure manifold 6, a rotor pump assembly 7, a mixing device 10, a hydraulic station 11, and a screw feeder 12 are integrated. The modular skid 1 design solves the problems of traditional skid-mounted equipment having dispersed functions, large footprint, and difficult relocation.

[0017] The skid 1 is equipped with lifting points at both the bottom and top, allowing for flexible selection of lifting methods depending on the transportation scenario. The protective railing on the top of the skid 1 features a tiltable structure, which can be tilted down during transportation to reduce space occupation and stood upright during operation to ensure operational safety. Furthermore, all system pipelines are prefabricated and connected in the factory, requiring only external interface connection on-site, reducing the installation and commissioning cycle by more than 60%, making it particularly suitable for scenarios requiring rapid deployment, such as offshore platforms and oil fields.

[0018] The variable frequency distribution cabinet 2 is equipped with a frequency converter, a soft starter, a circuit breaker, a contactor, and an air conditioner. The frequency converter is used to adjust the speed of each variable frequency motor and can protect the motor; the soft starter is used to control the motor of the hydraulic station 11, which mainly drives the screw feeder 12; the programmable controller can collect external sensor parameters, compare operating parameters, and then control all frequency converters and soft starters through Ethernet communication.

[0019] The pneumatic system 3 includes an air compressor, solenoid valves, pneumatic pipelines, and pneumatic valves.

[0020] The centrifugal pump assembly 4 uses a permanent magnet variable frequency motor for direct drive, which enables centrifugal pump speed regulation.

[0021] Powder silo 5 is equipped with a feeding port, a powder storage tank, a vibrating hammer, a discharge port, and a vent valve. It is fully enclosed during operation, facilitating construction in rainy weather. Powder silo 5 adopts a fully enclosed structure, equipped with a sealing cap for the feeding port, a vent valve, and a vibrating hammer, preventing dust leakage during operation and improving the operating environment; the vibrating hammer can prevent dry powder bridging and blockage, ensuring feeding stability.

[0022] The low-pressure manifold 6 is made of seamless steel pipe and can transport powder materials. The pipeline is equipped with pressure sensors, flow meters and water quality detectors, and can transmit data to the monitoring system.

[0023] The rotor pump assembly 7 is equipped with a permanent magnet variable frequency motor, a reducer, and a cam pump. The permanent magnet variable frequency motor and the reducer are connected, and then the reducer is connected to the rotor pump, which can adjust the speed and displacement of the rotor pump.

[0024] Vertical centrifugal pump assembly 8 (standby pump) is equipped with a motor-driven vertical centrifugal pump as an emergency liquid supply unit. It adopts a motor-driven design. When centrifugal pump assembly 4 fails, the intelligent monitoring system can automatically switch to the vertical centrifugal pump to ensure that the mixing process is not interrupted and to be used for emergency liquid supply.

[0025] The liquid filling unit 9 is equipped with a permanent magnet variable frequency motor, a reducer and a cam pump. The permanent magnet variable frequency motor and the reducer are connected, and then the reducer is connected to the rotor pump, which can adjust the speed and displacement of the rotor pump assembly 7.

[0026] The mixing device 10 is equipped with a wetting funnel 16 at the powder inlet. The dry powder is pre-wetted and dispersed through the wetting funnel 16. Then, through multi-stage jet mixing technology, the pre-dispersed dry powder and water are fully mixed by the jet negative pressure formed by the high-pressure water flow. This solves the problems of agglomeration and uneven mixing that are easy to occur in traditional stirring and mixing. The final high-concentration polymer solution has good uniformity and no water encapsulation phenomenon, and the mixing efficiency is greatly improved.

[0027] The hydraulic station 11 includes a motor, a hydraulic oil tank, a cooling fan, a hydraulic piston pump, and a hydraulic motor. The hydraulic motor is used to drive the screw feeder 12, which is assisted by the hydraulic station 11 (motor driven). Compared with the electric motor, the hydraulic motor is smaller in size and has stronger dust and vibration resistance. It can stably convey dry powder even under harsh working conditions, further improving the reliability of the equipment.

[0028] The screw feeder 12 is driven by the hydraulic motor of the hydraulic station 11 and includes a set of conveying screws and two sets of auxiliary screws. The conveying screws can accurately measure and convey polymer dry powder.

[0029] In this embodiment, the powder outlet of the powder tank 5 is connected to the powder inlet of the mixing device 10 through the screw feeder 12. The hydraulic motor in the hydraulic station 11 drives the screw feeder 12 to transport the polymer dry powder in the powder tank 5 to the mixing device 10. The liquid outlet of the centrifugal pump assembly 4 is connected to the liquid inlet of the mixing device 10. Clean water enters the centrifugal pump 4 through the suction manifold 14 and enters the mixing device 10 after being pressurized by the centrifugal pump 4. The mixing outlet of the mixing device 10 is connected to the rotor pump assembly 7 through the low-pressure manifold 6. After the dry powder and clean water are mixed in the mixing device 10, they are discharged outward through the rotor pump assembly 7.

[0030] In this embodiment, the vertical centrifugal pump assembly 8 is used as a standby pump and is connected in parallel with the centrifugal pump assembly 4, with a valve separating them.

[0031] The suction manifold 14 is connected to the inlet of the centrifugal pump assembly 4 and the vertical centrifugal pump assembly 8. A valve separates the inlets of the centrifugal pump assembly 4 and the vertical centrifugal pump assembly 8. During operation, clean water enters the centrifugal pump assembly 4 through the suction manifold 14, is pressurized by the centrifugal pump assembly 4, and is then discharged. A flow meter 15 is installed at the discharge outlet of the centrifugal pump assembly 4 to accurately measure the clean water flow rate in real time. After passing through the flow meter 15, the clean water enters the mixing device 10. The mixing device 10 has two clean water inlets and one discharge outlet. Additionally, the mixing device 10 has a powder inlet. The material inlet is connected to the wetting funnel 16; the inlet of the wetting funnel 16 is connected to the outlet of the screw feeder 12. Dry powder is discharged through the screw feeder 12 and enters the wetting funnel 16. The moistened dry powder and clean water enter the mixing device 10 together. After mixing, a viscous liquid is formed. The outlet of the mixing device 10 is connected to the inlet of the rotor pump assembly 7. The mixed liquid is discharged outward through the rotor pump assembly 7. The outlet of the rotor pump assembly 7 is connected to the outlet manifold 17. The outlet manifold 17 is provided with multiple connection ports, which can be used for connecting equipment and emergency discharge. The vertical centrifugal pump assembly 8 can draw clean water from the suction manifold 1 for emergency discharge.

[0032] The polymer mixing skid device control system of the present invention also includes an intelligent monitoring system 13. The intelligent monitoring system 13 includes a main control unit, a local operation interface, a metering sensor unit, a software system, a remote monitoring module, and a communication interface; it can realize local operation of the equipment, real-time monitoring and recording of data, and also remote control. Key power units such as the centrifugal pump assembly 4, the rotor pump assembly 7, and the liquid addition unit are all directly driven by permanent magnet variable frequency motors. Motor drives have the characteristics of fast response speed and high control precision, enabling more precise adjustment of equipment operating parameters. They are also smaller in size and 20%-30% more energy-efficient than traditional asynchronous motors. Through unified control by the frequency converter in the variable frequency distribution cabinet 2, the motor speed can be intelligently adjusted in real time according to mixing requirements (such as different concentrations of polymer solutions and different flow outputs), achieving precise control of the displacement of the centrifugal pump assembly 4 and the rotor pump assembly 7. For example, in the liquid addition unit, the permanent magnet variable frequency motor drives the cam pump through a reducer, which can control the additive addition accuracy within ±1%, solving the problems of lag and low precision in traditional hydraulic drive displacement adjustment. The intelligent control system, built around a programmable logic controller (PLC), can automatically adjust the operating status of various power equipment based on parameters such as powder-liquid ratio, and monitor equipment operating data in real time, such as motor speed, flow rate, and pressure. Through an integrated monitoring interface, operators can remotely and clearly understand the overall operation of the equipment, promptly identifying and handling potential faults. When equipment malfunctions, the system can automatically issue alarms and take corresponding protective measures, reducing manual intervention, lowering labor intensity, and improving production safety and continuity. In large-scale industrial production sites, operators can remotely operate and monitor mixing equipment from the control room, achieving efficient production management. The intelligent monitoring system integrates metering sensing units (pressure sensors, flow meters, water quality analyzers), core area cameras, and Ethernet communication modules to achieve a closed loop of "data monitoring-analysis-control-feedback." The local operating interface can display multiple parameters in real time, such as powder-liquid ratio, motor speed, and pipeline pressure; the remote monitoring module connects to the PLC in the platform control cabinet via Ethernet, supporting remote adjustment of mixing parameters, equipment start / stop, and fault diagnosis. For example, when the water quality analyzer in low-pressure manifold 6 detects excessive hardness in the purified water, the system automatically issues a warning and adjusts the dosage of additives in the liquid additive system to ensure solution quality. The equipment has a built-in intelligent fault diagnosis module that provides warnings for specific system units. For instance, when the inverter in rotor pump assembly 7 detects motor overload, it immediately locates the faulty unit and prompts for inspection of the reducer or cam pump. Furthermore, through real-time analysis of sensor data, it can quickly and accurately determine whether equipment components are malfunctioning, such as assessing the operating status of critical components like the water-powder mixing device 10 and the centrifugal pump assembly 4. Once a fault is detected, an alarm is immediately issued and the fault location is pinpointed, facilitating rapid repair by maintenance personnel.Meanwhile, redundant design is adopted, such as setting up a backup water-powder mixing device 10 and a backup vertical centrifugal pump assembly 8. When the main equipment (centrifugal pump assembly 4) fails, the system can automatically switch to the backup equipment (vertical centrifugal pump assembly 8), ensuring uninterrupted mixing, effectively improving equipment reliability and production continuity, and reducing production stoppage losses caused by equipment failure. In some industrial production processes where production cannot be easily stopped, redundant design ensures smooth production. The programmable controller can collect feeder speed and flow meter data, compare them with the preset water-powder ratio, and adjust the speed of the electric water pump and discharge pump. It can also synchronously adjust the hydraulic motor speed of the screw feeder 12 (controlled by the hydraulic station motor), realizing the three-stage linkage control of "dry powder conveying - clean water supply - solution discharge", improving the mixing accuracy.

[0033] This invention focuses on the field of petroleum fracturing technology, addressing the core requirements of this field for "high uniformity, high stability, and continuous fluid supply" of polymer solutions, as well as the application characteristics of "high environmental protection requirements, flexible deployment, and remote controllability" in onshore oil fields and offshore platforms. The all-electric drive design solves the problem of diesel engine exhaust pollution, the highly skid-mounted design adapts to the rapid relocation needs of oilfield sites, and multi-stage jet mixing ensures the quality of the polymer solution used for fracturing. Ultimately, it achieves a technological breakthrough in "environmentally friendly, efficient, precise, and reliable" solutions, filling the technological gap in existing equipment in the field of petroleum fracturing.

[0034] Combination Figure 4-5 As shown, the polymer mixing skid device control system of the present invention is equipped with an automatic controller connected to the manual control terminal. The automatic controller is connected to a signal unit, a powder conveying unit, a valve control unit, a hydraulic drive unit, a suction pump control unit, and a discharge pump control unit.

[0035] The automatic controller collects data, and the operator sets the discharge temperature through the human-machine interface. The automatic controller automatically adjusts the suction pump (centrifugal pump assembly 4) and discharge pump (rotary pump assembly 7), and controls the powder conveying unit and valve control unit. Based on the set powder ratio, the automatic controller controls the rotation speed of the screw feeder 12 to achieve precise material feeding. The automatic controller is also connected to the valve control unit, which provides hydraulic power to the entire skid via a hydraulic drive unit. In this embodiment, the automatic controller is an ALLEN BRADLEY model 1769-L33ER.

[0036] After control begins, the automatic controller compares the data from the signal unit with the set pressure and flow rate in the automatic controller to confirm the operation of the suction pump control unit and the discharge pump control unit.

[0037] The present invention provides a control method for a polymer blending skid device control system, comprising the following steps: S1. Parameter setting: After starting the automatic controller, set the liquid dispensing rate, water-powder ratio, and liquid addition ratio through the manual control terminal in the human-machine interface; S2. System self-test: The automatic controller collects signals from various sensors (mainly flow and pressure signals) to determine whether the equipment meets the start-up conditions; it collects the speed, suction flow, discharge pressure, water quality parameters and valve status signals of the screw feeder 12 to determine whether the system is in a safe state. If an abnormality is detected, it enters the alarm or protection mode; if the detection is normal, it sequentially controls the rotor pump assembly 7 and the centrifugal pump assembly 4 to enter the working state. S3. Sequential Start-up: Start the hydraulic pump, centrifugal pump assembly 4, mixing device 10 and rotor pump assembly 7 of hydraulic station 11 in sequence according to preset logic. S4. Powder control: Adjust the powder feeding amount in real time based on the theoretical powder feeding amount and the feedback of the screw feeder 12 auger speed; S5, Liquid Addition Control: Precise closed-loop control of additive flow rate is achieved through flow meter 15 and proportional valve; S6. Process control: Dynamically adjust each actuator, compare the actual liquid mixing parameters with the set value in real time, and dynamically adjust each actuator through PID algorithm to maintain the stability of system pressure, flow rate and mixing ratio; S7. Safety Protection: Automatic alarm when real-time monitoring values ​​are abnormal; S8. Operation complete: Automatically clear the cumulative amount and reset the equipment.

[0038] The foregoing has shown and described the basic principles and main structural features of the present invention. The present invention is not limited to the above examples; various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A control system for a polymer blending skid device, comprising a skid frame, characterized in that: The skid (1) integrates a centrifugal pump assembly (4), a powder tank (5), a rotor pump assembly (7), a mixing device (10), and a screw feeder (12). The powder outlet of the powder tank (5) is connected to the powder inlet of the mixing device (10) through the screw feeder (12). The hydraulic motor in the hydraulic station (11) drives the screw feeder (12) to transport the polymer dry powder in the powder tank (5) to the mixing device (10). The outlet of the centrifugal pump assembly (4) is connected to the inlet of the mixing device (10). Clean water enters the centrifugal pump (4) through the suction manifold (14), and enters the mixing device (10) after being pressurized by the centrifugal pump (4). The mixing outlet of the mixing device (10) is connected to the rotor pump assembly (7) through the low-pressure manifold (6). After the dry powder and water are mixed in the mixing device (10), they are discharged out through the rotor pump assembly (7).

2. The control system for the polymer blending skid device according to claim 1, characterized in that: The skid (1) also integrates a vertical centrifugal pump assembly (8), which serves as a backup pump and is connected in parallel with the centrifugal pump assembly (4), with a valve separating them.

3. The control system for the polymer blending skid device according to claim 1, characterized in that: A flow meter (15) is installed at the outlet of the centrifugal pump assembly (4).

4. The control system for the polymer blending skid device according to claim 1, characterized in that: A wetting funnel (16) is provided between the screw feeder (12) and the mixing device (10). The dry powder is discharged through the screw feeder (12) and enters the wetting funnel (16), and after being moistened, it enters the mixing device (10).

5. The control system for the polymer blending skid device according to claim 1, characterized in that: The skid (1) also integrates a liquid filling unit (9) for adjusting the speed and displacement of the rotor pump assembly (7).

6. A control method for a polymer blending skid device control system as described in any one of claims 1 to 5, characterized in that: Includes the following steps: S1. Parameter setting: Set the liquid dispensing rate, water-powder ratio, and liquid addition ratio through the human-machine interface; S2. System self-test: Collect signals from each sensor to determine whether the device meets the start-up conditions; S3. Sequential Start-up: Start the hydraulic pump, centrifugal pump assembly (4), mixing device (10) and rotor pump assembly (7) of the hydraulic station (11) in sequence according to the preset logic. S4. Powder control: Adjust the powder feeding amount in real time based on the theoretical powder feeding amount and the feedback of the screw feeder (12) auger speed; S5, Liquid Addition Control: Precise closed-loop control of additive flow rate is achieved through flow meter (15) and proportional valve; S6. Process Regulation: Dynamically regulate each actuator to maintain stable system pressure, flow rate and ratio; S7. Safety Protection: Automatic alarm when real-time monitoring values ​​are abnormal; S8. Operation complete: Automatically clear the cumulative amount and reset the equipment.

7. The control method of the polymer blending skid device control system according to claim 6, characterized in that: The specific steps of S2 are as follows: collect the rotation speed, suction flow rate, discharge pressure, water quality parameters and valve status signals of the screw feeder (12), determine whether the system is in a safe state, and if an abnormality is detected, enter the alarm or protection mode; if the detection is normal, control the rotor pump assembly (7) and the centrifugal pump assembly (4) to enter the working state in sequence.

8. The control method of the polymer blending skid device control system according to claim 6, characterized in that: The specific steps of S6 are as follows: compare the actual liquid preparation parameters with the set values ​​in real time, and dynamically adjust each actuator through the PID algorithm to maintain the stability of system pressure, flow rate and ratio.

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