Device for measuring thickness of liquid film in pipe

Abstract

The utility model relates to the field of liquid film thickness measurement, and provides a device for measuring the thickness of a liquid film in a tube. The device comprises an annular fixer, a linear motor, a stepping motor, a probe and the like. And the annular fixer fixes the test tube through a bolt and adapts to different tube diameters. The linear motor drives the harness cord and the stepping motor to achieve circumferential and axial movement of the probe, and three-dimensional accurate positioning of the probe is completed. The probe is in contact with the liquid film and the pipe wall to form a closed circuit, and the moving state of the probe is monitored through current changes. The device can realize automatic, precise and multi-point distribution measurement of the thickness of the liquid film in the vertical pipe type evaporator pipeline, has the advantages of simple structure, convenience in operation, stability, reliability, strong applicability and low cost, and is widely applied to measurement and analysis of the thickness of the industrial liquid film.

Description

Technical Field

[0001] This utility model relates to the field of liquid film thickness measurement, specifically to a device for measuring the thickness of a liquid film inside a tube. Background Technology

[0002] Water is the source of life, the most important natural resource on Earth, and the foundation for the survival of humans and other life forms. Currently, my country faces a severe shortage of clean water resources, making wastewater desalination crucial for addressing this scarcity. Existing wastewater desalination technologies include distillation, reverse osmosis, electrolysis, and ion exchange. Among these, low-temperature multi-effect evaporation is widely used due to its low water quality requirements and ease of operation. Liquid film thickness is one of the key factors affecting the heat exchange efficiency of low-temperature multi-effect evaporators. A thinner liquid film reduces thermal resistance during falling film evaporation, thus increasing heat exchange efficiency; a thicker liquid film improves membrane stability, making it less prone to rupture or failure, thereby improving separation and evaporation efficiency. Existing liquid film measurement methods include laser methods, ultrasonic methods, and spectroscopic confocal methods. However, these methods are costly and difficult to operate when measuring the liquid film thickness inside vertical tube falling film evaporators in industrial applications. This study aims to investigate the impact of the liquid film thickness inside the tubes of a vertical tube falling film evaporator on the heat exchange efficiency of a low-temperature multi-effect evaporator during the falling film evaporation process. Therefore, there is a need for a measuring device that is low in cost, easy to operate, highly automated, and capable of quickly and accurately measuring the thickness of the liquid film on the surface of different locations inside the heat exchange tube during the demolding evaporation process. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, this utility model provides a device for measuring the thickness of liquid film inside a tube.

[0004] In a first aspect, the present invention provides a method for measuring the thickness of a liquid film inside a tube. The method includes:

[0005] By combining a probe with a stepper motor, precise measurement of liquid film thickness is achieved through probe movement controlled by electrical signals. This method utilizes a closed circuit formed by the probe's contact with the liquid film and the metal tube wall, reflecting changes in the contact state between the probe and the liquid film through current variations. During measurement, the probe initially makes direct contact with the tube wall, resulting in the highest ammeter reading. As the stepper motor drives the probe away from the inner wall, the circuit resistance gradually increases due to the presence of the liquid film, causing the current to gradually decrease. When the probe completely detaches from the liquid film, the circuit breaks, and the current drops to zero. The total distance traveled by the stepper motor at this point represents the thickness of the liquid film.

[0006] Secondly, this utility model provides a device for measuring the thickness of a liquid film inside a tube. The device includes:

[0007] 1. Test tube, 2. Ring retainer, 3. Threaded through hole, 4. Test tube clearance hole, 5. Linear motor, 6. Linear motor retainer, 7. Through wire, 8. Fixing clip, 9. Stepper motor, 10. Through wire stabilizer, 11. Probe, 12. Power supply, 13. Ammeter, 14. Switch, 15. Electrical wire, 16. Data cable, 17. Computer, 18. Miniature camera.

[0008] The annular retainer 2 is provided with a threaded through hole 3, the test tube 1 passes through the test tube clearance hole 4, the bolt is connected to the threaded through hole 3 and fixes the test tube 1 to the annular retainer 2; the annular retainer 2 and the linear motor retainer 6 are provided with threaded holes, the linear motor retainer 6 is connected to the annular retainer 2 by bolts and fixes the linear motor 5 to the annular retainer 2.

[0009] The through wire 7 is further connected to the fixing clip 8 by welding. The fixing clip 8 is provided with screw holes, and the two ends of the clip 8 are connected by bolts to clamp and fix the stepper motor 9 and miniature camera 18 in the middle. The through wire stabilizer 10 is provided with threaded holes, and the through wire stabilizer 10 is connected to the test tube 1 by bolts; the end face of the through wire stabilizer is provided with a hole of the same diameter as the through wire 7, and the through wire 7 is limited through the small hole.

[0010] The probe 11 and the test tube 1 are further connected to the positive and negative terminals of the power supply 12 via wires 15, and an ammeter 13 and a circuit switch 14 are provided on the wires 15; the stepper motor 9, the linear motor 5 and the miniature camera 18 are connected to the computer 17 via a data cable 16.

[0011] Compared with existing liquid film thickness measuring devices, this invention has the following advantages.

[0012] A device for measuring the thickness of a liquid film inside a tube is disclosed. This method incorporates a stepper motor, which is combined with a probe. The probe's position is precisely controlled via electrical signals, resulting in more stable and accurate liquid film thickness measurements. Furthermore, the device has a simple structure that is easy to modify; the device structure can be altered according to engineering requirements, and stepper motors of different specifications and accuracies can be replaced based on specific engineering needs and the range of liquid film thickness.

[0013] 2. A device for measuring the thickness of a liquid film inside a tube. The design of the measuring device enables it to measure the liquid film thickness at different circumferential angles and axial positions within the tube, thereby comprehensively understanding the liquid film thickness distribution and improving the comprehensiveness of the measurement. The circumferential and axial movements of the probe are driven by a computer-controlled motor, which not only makes the device highly automated but also allows for more precise and easier control of the probe's three-dimensional movement.

[0014] 3. A device for measuring the thickness of a liquid film inside a tube, wherein a miniature camera is installed around a stepper motor to directly observe the flow state of the liquid film inside the tube.

[0015] 4. A device for measuring the thickness of a liquid film inside a tube, which is less expensive, more stable and reliable than traditional measuring devices, and has a higher degree of automation, making it more suitable for accurate measurement of surface liquid film thickness in industrial production. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a measuring device for measuring the thickness of a liquid film inside a tube, according to the present invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] In the description of this utility model, it should be noted that the terms "top," "bottom," "one side," "the other side," "front," "back," "middle part," "inner," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] like Figure 1 The image shows a measuring device for measuring the thickness of a liquid film inside a tube, comprising a test tube 1, an annular retainer 2, a threaded through hole 3, a test tube clearance hole 4, a linear motor 5, a linear motor retainer 6, a through wire 7, a fixing clip 8, a stepper motor 9, a through wire stabilizer 10, a probe 11, a power supply 12, an ammeter 13, a switch 14, a wire 15, a data cable 16, a computer 17, and a miniature camera 18.

[0020] Specifically, the liquid film thickness measuring device of this scheme includes annular retainers 2 at both ends. The annular retainers 2 are circular in shape, with a test tube clearance hole 4 in the center to allow test tubes of different diameters to pass through. The surface of the annular retainer 2 has three evenly distributed threaded through holes 3 for mounting bolts. These bolts extend into the test tube clearance hole 4 through the threaded through holes 3, directly pressing the test tube 1 to secure it. This design allows the device to adapt to test tubes 1 of different outer diameters, providing greater versatility and flexibility. The cross-section of the annular retainer has threaded holes for connecting and fixing the linear motor 5 to the linear motor retainer 6 via bolts. The linear motor retainer 6 is spaced a certain distance from the test tube 1 to facilitate liquid injection into the test tube 1.

[0021] The through wire 7 is welded to the fixing clamp 8, which has a threaded hole. The two clamps 8 are bolted together to clamp and fix the stepper motor 9 and the miniature camera 18 in the middle. Simultaneously, the through wire 7 is connected to the linear motor 5. The linear motor 5 rotates the through wire 7 to drive the stepper motor 9 to move horizontally. Due to the very small thread pitch of the through wire 7, although the stepper motor 9 experiences axial movement during circumferential movement, the movement is minimal and negligible. The through wire stabilizer 10 has a threaded hole and is bolted to the test tube 1. The end face of the through wire stabilizer has a hole of the same diameter as the through wire 7, through which the through wire 7 is limited.

[0022] The probe 11 and the test tube 1 are connected to the positive and negative terminals of the power supply 12 respectively via the wire 15, and the wire 15 is equipped with an ammeter 13 and a circuit switch 14; the stepper motor 9, the linear motor 5 and the miniature camera 18 are connected to the computer 17 via the data cable 16.

[0023] The measurement process of the liquid film thickness measuring device in this scheme is as follows: First, the annular retainer 2 is installed onto the test tube 1, so that the test tube 1 passes through the test tube clearance hole 2, and the test tube 1 is fixed to the annular retainer 2 with bolts. While tightening the bolts, the tightness of the bolts is adjusted to ensure that the annular retainer 2 and the test tube 1 are firmly connected to avoid displacement or shaking of the test tube during subsequent measurement. Next, the linear motor retainer 6 is aligned and fixed with the threaded hole on the annular retainer 2 using bolts, and the linear motor 5 is installed on the linear motor retainer 6.

[0024] The center of the fixing clip 8 is precisely welded to the through wire 7. The two clips 8 are then connected by bolts, clamping and fixing the stepper motor 9 and miniature camera 18 in the middle. During installation, the bolts should not be overtightened to avoid damaging the electronic components. The through wire 7 is then connected to the horizontal motor 5. The through wire stabilizer 10 has a threaded hole, which is then bolted to the test tube 1. The end face of the through wire stabilizer has a hole of the same diameter as the through wire 7, through which the through wire 7 is limited.

[0025] Connect probe 11 to the positive and negative terminals of power supply 12 via wires 15. Simultaneously, connect ammeter 13 and circuit switch 14 to the circuit to monitor current changes when the probe contacts the liquid film. Connect rotary motor 5, linear motor 5, and stepper motor 9 to computer 17 via data cable 16. Start the control program on computer 17 to initialize the equipment.

[0026] Linear motor 5 drives the guide wire 7 to move to a predetermined position, ensuring that the initial position of probe 11 remains consistent along the axial direction of the test tube. Stepper motor 9 adjusts probe 11 to a position away from the surface of test tube 1, ensuring the initial accuracy of the vertical measurement process. Simultaneously, miniature camera 18 is activated and its focus is adjusted to ensure clear image capture.

[0027] The computer control program is activated, driving stepper motor 9 to move probe 11 gradually closer to the wall of test tube 1. When probe 11 contacts the wall of test tube 1, the circuit is activated, and ammeter 13 displays the current at its maximum value. This state is used to calibrate the initial contact position of probe 11. Computer 17 controls stepper motor 9 to drive probe 11 away from the tube wall in set steps. During this process, due to the presence of the liquid film, the resistance between probe 11 and the inner wall of test tube 1 gradually increases, and the reading of ammeter 13 gradually decreases. When probe 11 moves a certain distance and the reading of ammeter 13 suddenly drops to zero, it indicates that probe 11 has completely detached from the liquid film, and the circuit is broken. At this time, computer 17 records the distance moved by stepper motor 13, which is the thickness of the liquid film.

Claims

1. A device for measuring the thickness of a liquid film inside a tube, comprising a test tube (1), an annular retainer (2), a threaded through hole (3), a test tube clearance hole (4), a linear motor (5), a linear motor retainer (6), a through wire (7), a fixing clip (8), a stepper motor (9), a through wire stabilizer (10), a probe (11), a power supply (12), an ammeter (13), a switch (14), a wire (15), a data cable (16), and a computer (17); characterized in that: The annular retainer (2) is provided with a threaded through hole (3), and the test tube (1) passes through the test tube clearance hole (4). The bolt is connected to the threaded through hole (3) and fixes the test tube (1) to the annular retainer (2). The annular retainer (2) and the linear motor retainer (6) are provided with threaded holes. The linear motor retainer (6) is connected to the annular retainer (2) by bolts and fixes the linear motor (5) to the annular retainer (2). The linear motor (5) is connected to the through wire (7), and the linear motor (5) drives the through wire (7) to move horizontally. The through wire (7) is connected to the fixing clamp (8) by welding. The fixed clamps (8) at both ends are connected by bolts and the stepper motor (9) is clamped in the middle and fixed. The wire stabilizer (10) is provided with threaded holes and is connected to the test tube (1) by bolts. The end face of the wire stabilizer is provided with a hole of the same diameter as the wire (7) and the wire (7) is limited by the small hole. The probe (11) and the test tube (1) are connected to the positive and negative terminals of the power supply (12) by wires (15) respectively, and the wires (15) are provided with an ammeter (13) and a circuit switch (14). The stepper motor (9) and the linear motor (5) are connected to the computer (17) by a data cable (16).

2. A device for measuring the thickness of a liquid film in a pipe according to claim 1, characterized in that: The linear motor (5) drives the through wire (7) to move horizontally, and the movement of the through wire (7) is a rotational horizontal movement; the movement of the through wire (7) drives the fixed clamp (8) and the stepper motor (9) to move, thereby driving the probe (11) to move along the axial and circumferential directions of the test tube (1).

Images