A sorting device for producing quartz sand for oil fracturing

Abstract

The application relates to the technical field of screening devices, and discloses a sorting device for quartz sand production for oil fracturing, which comprises a sieve cylinder, a main driving mechanism for driving the sieve cylinder to rotate and an auxiliary feeding mechanism. The auxiliary feeding mechanism comprises a feeding cylinder, an independent driving unit, an impact force detection unit and a controller. The feeding cylinder is coaxially arranged in the feeding section of the sieve cylinder and can rotate independently of the sieve cylinder. The independent driving unit is in transmission connection with the feeding cylinder and is used for driving the feeding cylinder to rotate at an adjustable rotating speed. The impact force detection unit is used for capturing the impact signals borne by the sieve screen in real time, and the controller is used for automatically identifying the impact events. When concentrated impact is generated due to the batch feeding of materials, the rotating speed of the feeding cylinder can be automatically increased, the quartz sand is uniformly dispersed by centrifugal force, and then the quartz sand is sent into the sieve cylinder, so that the concentrated impact of the materials on the sieve screen is avoided, the materials are prevented from being accumulated in the feeding section of the sieve cylinder, and the materials can be fully dispersed before being screened.

Description

Technical Field

[0001] This invention relates to the field of screening equipment technology, and more specifically, to a sorting device for the production of quartz sand for oil fracturing. Background Technology

[0002] In the production process of quartz sand for oil fracturing, the crushed and ground quartz sand particles need to be screened and graded to obtain fracturing proppant that meets specific particle size requirements. A drum screen is a commonly used sorting device. It uses a rotating drum to tumble and disperse the material on the screen mesh. Fine particles pass through the screen and fall, while coarse particles move axially along the drum and are discharged.

[0003] However, in actual production, the supply of quartz sand is usually intermittent and batch-based, for example, by pouring it into the feed hopper via a hoist hopper or loader bucket before it falls into the screen cylinder. This feeding method causes a large amount of material to rush into the feed end of the screen cylinder in a short period of time, creating a concentrated and high-intensity impact on the screen mesh, which leads to the following problems: the screen mesh is subjected to huge impact loads locally, making it prone to damage, deformation, or fatigue fracture, which shortens the service life of the screen mesh and increases maintenance costs; at the same time, the concentrated material drop causes the material to accumulate in the feed section and be pushed out of the screen mesh before it can be fully dispersed, resulting in a decrease in the effective screening area utilization and screening efficiency.

[0004] Currently, to alleviate the problem of concentrated material impact, existing technologies use methods such as adding a fixed material distribution cone at the feed inlet or adding a buffer pad under the screen. Although the material distribution cone can play a certain role in diverting the flow, it is passive, has limited effect, and suffers from severe wear. The buffer pad, on the other hand, cannot fundamentally disperse the material.

[0005] Therefore, there is an urgent need for an automated sorting device that can actively sense and respond to material impacts. Summary of the Invention

[0006] The purpose of this invention is to provide a sorting device for the production of quartz sand for oil fracturing, in order to solve the aforementioned technical problems.

[0007] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0008] This invention provides a sorting device for producing quartz sand for oil fracturing, comprising: a support frame, a screen cylinder rotatably mounted on the support frame, a main drive mechanism for driving the screen cylinder to rotate, wherein the screen cylinder is divided into a feeding section and a screening section along the axial direction, and also includes an auxiliary feeding mechanism;

[0009] The auxiliary feeding mechanism includes:

[0010] The feed cylinder is coaxially arranged inside the feed section of the screen cylinder and can rotate independently of the screen cylinder. The inner wall of the feed cylinder is provided with detachable spiral pusher fins.

[0011] An independent drive unit, connected to the feed cylinder drive, is used to drive the feed cylinder to rotate at an adjustable speed;

[0012] The impact force detection unit is used to acquire a detection signal that characterizes the magnitude of the impact force of the material on the screen of the screen cylinder;

[0013] The controller is electrically connected to the impact force detection unit and the independent drive unit, and is configured as follows:

[0014] Identify the occurrence and termination of material impact events based on detection signals;

[0015] When an impact event is detected, the independent drive unit is controlled to increase the rotation speed of the feed cylinder in order to use centrifugal force to disperse the material and reduce the concentrated impact on the screen.

[0016] When the impact event is detected to have ended, the independent drive unit is controlled to reduce the speed of the feed cylinder to the preset reference speed.

[0017] Furthermore, the impact force detection unit is a weighing sensor, a triaxial accelerometer, or a vibration velocity sensor mounted on a support frame.

[0018] Furthermore, the controller identifies impact events by comparing the detected signal with a dynamic impact threshold, which is updated in real time based on the statistical characteristics of the detected signal over a period of time.

[0019] Furthermore, the controller calculates the moving average and standard deviation of the detection signal over the most recent time period, and sets the dynamic impact threshold as the product of the moving average, the sensitivity coefficient, and the standard deviation.

[0020] Furthermore, when the controller increases the rotational speed of the feed cylinder, it determines the speed increment proportionally based on the magnitude of the detection signal exceeding the dynamic impact threshold.

[0021] Furthermore, the controller limits the rate of change of rotational speed when it increases by a preset acceleration ramp function, and limits the rate of change of rotational speed when it decreases by a preset deceleration ramp function, wherein the rate of change of the acceleration ramp function is greater than the rate of change of the deceleration ramp function.

[0022] Furthermore, the feed cylinder is cylindrical and is fixed to the support frame by a bearing seat.

[0023] Furthermore, the axial extension length of the feed cylinder does not exceed 50% of the total axial length of the feed section of the screen cylinder.

[0024] Furthermore, the inner wall of the feed cylinder is provided with detachable wear-resistant spiral pusher fins, and the spiral pusher fins and the feed cylinder are made of highly wear-resistant alloy materials.

[0025] Furthermore, a gear ring is provided on the outer periphery of the feed cylinder, and the independent drive unit includes a variable frequency geared motor, the output end of which is driven by a gear in conjunction with the gear ring.

[0026] The beneficial effects of this invention are as follows:

[0027] This device captures the impact signals received by the screen in real time through an impact force detection unit. Combined with the controller's automatic identification of impact events, it automatically increases the feed cylinder speed when a concentrated impact occurs due to a large influx of material. Centrifugal force is used to quickly and evenly disperse the concentrated quartz sand before it is fed into the screen cylinder. This avoids concentrated impact on the screen, reducing the probability of screen breakage and deformation, extending the screen's lifespan, and reducing maintenance costs. It also prevents material accumulation in the feed section of the screen cylinder, allowing for thorough dispersion before screening, improving the utilization rate of the screen's effective screening area and ensuring screening efficiency. After the impact event, the speed automatically returns to the baseline speed, avoiding unnecessary energy waste caused by prolonged high speeds. It is suitable for intermittent batch feeding production scenarios, exhibiting a high degree of automation and good adaptability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the sorting device for producing quartz sand for oil fracturing according to the present invention;

[0029] Figure 2 This is a side view of the sorting device for producing quartz sand for oil fracturing according to the present invention;

[0030] Figure 3 This is a schematic diagram of the auxiliary feeding structure in the sorting device for producing quartz sand for oil fracturing according to the present invention;

[0031] Figure 4 This is a cross-sectional view of the auxiliary feeding mechanism and a partial position of the screen cylinder in the sorting device for producing quartz sand for oil fracturing according to the present invention.

[0032] Figure 5 This is a system connection block diagram of the sorting device for producing quartz sand for oil fracturing according to the present invention;

[0033] Figure 6 This is a flowchart of the auxiliary feeding mechanism in the sorting device for producing quartz sand for oil fracturing according to the present invention.

[0034] In the diagram: 10, screen cylinder; 101, rotating main shaft; 20, support frame; 30, discharge hopper; 40, feed hopper; 50, main drive mechanism; 501, servo motor; 502, belt drive reduction structure; 503, sprocket drive structure; 60, auxiliary feeding mechanism; 601, feed cylinder; 602, spiral pusher fins; 603, gear ring; 604, variable frequency reduction motor; 605, gear; 606, weighing sensor. Detailed Implementation

[0035] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0036] Please refer to the following: Figures 1 to 6 The sorting device for producing quartz sand for oil fracturing provided in this embodiment of the invention includes: a screen cylinder 10, a support frame 20, a main drive mechanism 50, and an auxiliary feeding mechanism 60.

[0037] The screen cylinder 10 is a horizontal drum screen with a certain inclination angle, which is rotatably mounted on the top of the support frame 20. The main drive mechanism 50 is mounted on one end of the support frame 20. Specifically, the main drive mechanism 50 includes a servo motor 501, a pulley drive reduction structure 502, and a sprocket drive structure 503. The servo motor 501 is fixedly mounted on the support frame 20, and the output end of the servo motor 501 is connected to the pulley drive reduction structure 502. A rotating main shaft 101 along the length direction is provided on the central axis of one end of the screen cylinder 10, and the output end of the pulley drive reduction structure 502 is connected to the rotating main shaft 101 through the sprocket drive structure 503. The working process of the main drive mechanism 50 is as follows: the servo motor 501 outputs power, which is reduced and increased in torque by the belt drive reduction structure 502, and then the drive direction is changed by the sprocket drive structure 503, which drives the rotating main shaft 101 to rotate, thereby driving the entire screen cylinder 10 to rotate stably around its own axis at a preset speed, so that the quartz sand in the screen cylinder 10 can move slowly along the axial direction and continuously tumble, thus completing the screening operation.

[0038] The screen cylinder 10 is divided into a feeding section and a screening section along the axial direction. The screening section is equipped with multiple screens of different aperture sizes to achieve particle classification. A feed hopper 40 is installed above the feed end of the screen cylinder 10 and is fixed on the support frame 20. The feed hopper 40 guides the upstream sand into the feeding section. Below the screening section of the screen cylinder 10, multiple discharge hoppers 30 are arranged side by side to discharge the screened quartz sand separately.

[0039] An auxiliary feeding mechanism 60 is installed within the feeding section to provide active buffering and dispersion functions when material falls into the screen cylinder 10. Specifically, the auxiliary feeding mechanism 60 includes a feeding cylinder 601, an independent drive unit, and an impact force detection unit. The feeding cylinder 601 is cylindrical and coaxially arranged with the screen cylinder 10. It is fixed to the support frame 20 via a bearing seat, allowing it to rotate independently of the screen cylinder 10. Its axial extension length does not exceed 50% of the total length of the feeding section, ensuring that there is still an exposed screen surface for effective screening. A spiral pusher fin 602 is detachably fixed to the inner wall of the feeding cylinder 601. The rotation direction of the spiral pusher fin 602 is consistent with the rotation direction of the feeding cylinder 601 and the direction of material conveying to the screening section. It is used to apply forward thrust and circumferential dispersion force to the material during rotation. Both the spiral pusher fin 602 and the feeding cylinder 601 are made of high wear-resistant alloys, such as chromium-molybdenum alloy, to resist the erosion of quartz sand.

[0040] The independent drive unit includes a gear ring 603, a variable frequency geared motor 604, and a gear 605. The gear ring 603 is fixedly fitted onto the outer circumference of the feed cylinder 601, and the variable frequency geared motor 604 is fixed to the top of the bearing housing of the feed cylinder 601. Its output end meshes with the gear ring 603 through the gear 605. The variable frequency geared motor 604 is powered by a frequency converter, and the controller sends speed commands to the variable frequency geared motor 604 through the frequency converter to achieve continuous and precise adjustment of the speed of the feed cylinder 601.

[0041] The impact force detection unit is mainly used to acquire a detection signal characterizing the magnitude of the impact force of the material on the screen of the screen cylinder. It can be one or more combinations of a weighing sensor, a triaxial accelerometer, or a vibration velocity sensor. In this embodiment, a weighing sensor 606 is preferred. It is mounted on the support frame 20, specifically located in the area below the feeding section where the impact force is most concentrated. The weighing sensor 606 is used to detect the impact force generated on the screen when the material falls into the screen cylinder 10 in real time, and converts the force signal into an electrical signal and outputs it to the controller.

[0042] The controller can be a PLC or an industrial controller, electrically connected to the signal output terminal of the weighing sensor 606 and the inverter control terminal of the variable frequency geared motor 604, respectively. The controller internally stores and runs an impact buffer adaptive control algorithm, the details of which are as follows:

[0043] The core logic of the controller to implement active buffering is as follows, which is divided into three stages: perception, calculation, and execution.

[0044] 1. Perception layer:

[0045] The impact force signal output by the load cell 606 is sent to the analog input module of the controller via a transmitter. The controller performs a first-order low-pass filter on the signal every scan cycle (e.g., 50ms) to remove high-frequency noise and extract the true impact envelope. Simultaneously, the controller can also obtain the actual speed of the variable frequency geared motor 604 via feedback from the frequency converter, serving as a closed-loop reference.

[0046] It should be noted that the weighing sensor 606 in this device detects the instantaneous impact force signal of the material on the screen, rather than the static mass of the material inside the screen cylinder 10. The dynamic impact threshold adopts an adaptive baseline algorithm, which can automatically adapt to normal background fluctuations caused by the movement of the spiral pusher fins 602 and normal material flow, and only respond to real impact events that exceed the preset amplitude of the statistical baseline and last for more than the de-vibration time, thereby reliably distinguishing between normal screening fluctuations and concentrated impacts.

[0047] 2. Computation layer:

[0048] The controller first defines the baseline operating parameters: the preset baseline speed N0 of the feed cylinder 601 is about 15 rpm (adjustable on site), and this speed is maintained during normal operation.

[0049] The controller continuously calculates the dynamic impact threshold F th An adaptive baseline algorithm is used to avoid malfunctions caused by long-term material accumulation or sensor drift.

[0050] Take the moving average F of the filtered impact force signal within the most recent time window T (e.g., 30 seconds). avg and standard deviation σ.

[0051] The dynamic threshold is set to: F th =F avg +k×σ;

[0052] Where k is the sensitivity coefficient, which can initially be set to 1.5 to 2.0. The smaller the k value, the more sensitive the system is to impacts and the easier it is to trigger an accelerated response; the larger the k value, the less sensitive the system is, and it only responds to large impacts. The k value can be set in the human-machine interface according to the on-site working conditions.

[0053] For the first 30 seconds after the system powers on, a fixed threshold F will be used temporarily because the collected data is insufficient to calculate a valid moving average and standard deviation. th-0 =500N is used as a transition value, and the system will automatically switch to the above adaptive dynamic threshold after 30 seconds of data accumulation.

[0054] Impact event detection employs a de-jittering and release mechanism to prevent misjudgments caused by instantaneous signal spikes or brief dips.

[0055] Impact event initiation condition: When the instantaneous impact force F > F thAnd this condition continues for more than the de-jitter time t debounce At a time of 0.3 seconds, the "impact event begins" is determined.

[0056] The impact event ends when F ≤ F th -Δ (hysteresis Δ can be taken as 0.15F) th ), and this condition continues for more than the release time t. release When the time reaches 0.5 seconds, the "impact event ends".

[0057] The purpose of setting the hysteresis Δ is to prevent the system from repeatedly switching between start and stop states when the impact force fluctuates slightly around the threshold, thus ensuring control stability.

[0058] Once the impact event is detected, the controller immediately calculates the target rotational speed N of the feed cylinder 601. target The calculation formula is as follows:

[0059] N target =N0+ΔN max ×(FF th ) / F scale ;

[0060] In the formula:

[0061] ΔN max The maximum speed increase can be taken as 10-12 rpm, representing the maximum additional speed increase based on the base speed during the most intense impact; F is the filtered value of the current instantaneous impact force; F th This represents the current dynamic impact threshold; F scale The impact force scaling factor is the difference between the estimated maximum impact force and Fth. For example, it is set to 800N. It is used to normalize the impact force exceeding the threshold to a scaling factor between 0 and 1.

[0062] The formula means that the target rotational speed of the feed cylinder is linearly increased based on the reference rotational speed N0, according to the magnitude of the impact force exceeding the dynamic threshold. The greater the magnitude of the exceedance, the greater the speed increment, with a maximum not exceeding N0 + ΔN. max .

[0063] Calculated N target It needs to be limited to the range of 0-30 rpm. To avoid mechanical wear and system oscillation caused by excessively frequent speed adjustments, it should only be adjusted when N... target The new speed command will only be updated and output to the execution layer when the difference between the current actual speed and the speed command exceeds the dead zone (±2 rpm); otherwise, the current speed command will remain unchanged.

[0064] 3. Execution layer:

[0065] The target rotational speed calculated by the controller is not directly output, but is instead sent to the ramp generator module to limit the rate of change of rotational speed.

[0066] Acceleration ramp: approximately +10 rpm / s, ensuring that the target speed can be reached within 1 to 2 seconds when the impact occurs, providing a rapid response.

[0067] Deceleration ramp: approximately -5 rpm / s, to allow the rotational speed to gradually return to the baseline value after the impact, preventing the material from suddenly collapsing and causing a secondary impact.

[0068] The controller sends the speed command after the ramp to the frequency converter of the variable frequency reduction motor 604 via analog signal or communication. The variable frequency reduction motor 604 drives the feed cylinder 601 to rotate according to the command in speed mode. If the frequency converter fails or the motor is overloaded, the controller immediately sets the speed to zero and sends an alarm. At this time, the feed cylinder 601 stops rotating, but the screen cylinder 10 is still driven to rotate independently by the main drive mechanism 50, and the device can maintain production in a degraded manner.

[0069] The specific working process of the sorting device provided by this invention is as follows:

[0070] During normal screening, the feed cylinder 601 rotates smoothly at the reference speed N0. The spiral pusher fins 602 gently push the material forward and pre-disperse it. When intermittent feeding causes a sudden surge of material, the weighing sensor 606 immediately senses the sudden increase in impact force. The controller determines that an impact event has occurred and quickly increases the speed of the feed cylinder 601. The centrifugal force generated by the high-speed rotation throws the concentrated material clumps around the circumference, making them evenly adhere to the screen, thereby greatly reducing the local dense impact on the screen and protecting the screen. Once the impact has passed, the speed gradually drops back to the reference value, restoring the normal screening rhythm.

[0071] Under the above structure and control strategy, the device can realize real-time perception and active buffering of the impact caused by intermittent feeding, significantly extend the screen life, and not affect the original screening process, thus ensuring the continuous and efficient operation of the fracturing quartz sand production line.

[0072] The embodiments of the present invention have been described above, but the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention, all of which are within the protection scope of the present invention.

Claims

1. A sorting device for producing quartz sand for oil fracturing, comprising: The system comprises a support frame, a screen cylinder rotatably mounted on the support frame, and a main drive mechanism for driving the screen cylinder to rotate. The screen cylinder is divided into a feeding section and a screening section along the axial direction. The system is characterized by further including an auxiliary feeding mechanism. The auxiliary feeding mechanism includes: The feed cylinder is coaxially arranged inside the feed section of the screen cylinder and can rotate independently of the screen cylinder. The inner wall of the feed cylinder is provided with detachable spiral pusher fins. An independent drive unit, connected to the feed cylinder drive, is used to drive the feed cylinder to rotate at an adjustable speed; The impact force detection unit is used to acquire a detection signal that characterizes the magnitude of the impact force of the material on the screen of the screen cylinder; The controller is electrically connected to the impact force detection unit and the independent drive unit, and is configured as follows: Identify the occurrence and termination of material impact events based on detection signals; When an impact event is detected, the independent drive unit is controlled to increase the rotation speed of the feed cylinder in order to use centrifugal force to disperse the material and reduce the concentrated impact on the screen. When the impact event is detected to have ended, the independent drive unit is controlled to reduce the speed of the feed cylinder to the preset reference speed.

2. The sorting device for producing quartz sand for oil fracturing according to claim 1, characterized in that, The impact force detection unit is a weighing sensor, a triaxial accelerometer, or a vibration velocity sensor installed on a support frame.

3. The sorting device for producing quartz sand for oil fracturing according to claim 1, characterized in that, The controller identifies impact events by comparing the detected signal with a dynamic impact threshold, which is updated in real time based on the statistical characteristics of the detected signal over a period of time.

4. The sorting device for producing quartz sand for oil fracturing according to claim 3, characterized in that, The controller calculates the moving average and standard deviation of the detection signal over the most recent time period, and sets the dynamic impact threshold as the product of the moving average, the sensitivity coefficient, and the standard deviation.

5. The sorting device for producing quartz sand for oil fracturing according to claim 4, characterized in that, When the controller increases the rotational speed of the feed cylinder, it determines the speed increment proportionally based on the magnitude of the detection signal exceeding the dynamic impact threshold.

6. The sorting device for producing quartz sand for oil fracturing according to claim 1, characterized in that, The controller limits the rate of change of rotational speed when it increases by a preset acceleration ramp function and limits the rate of change of rotational speed when it decreases by a preset deceleration ramp function, and the rate of change of the acceleration ramp function is greater than the rate of change of the deceleration ramp function.

7. The sorting device for producing quartz sand for oil fracturing according to claim 1, characterized in that, The feed cylinder is cylindrical and is fixed to the support frame by a bearing seat.

8. The sorting device for producing quartz sand for oil fracturing according to claim 1, characterized in that, The axial extension length of the feed cylinder shall not exceed 50% of the total axial length of the feed section of the screen cylinder.

9. The sorting device for producing quartz sand for oil fracturing according to claim 1, characterized in that, The spiral pusher fins and feed cylinder are made of highly wear-resistant alloy materials.

10. The sorting device for producing quartz sand for oil fracturing according to claim 1, characterized in that, The outer circumference of the feed cylinder is provided with a gear ring, and the independent drive unit includes a variable frequency reduction motor. The output end of the variable frequency reduction motor is driven by the gear and the gear ring.

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