HU201606B - Level-measuring device - Google Patents

Abstract

FIELD OF THE INVENTION The present invention provides apparatus for measuring the level of granular, particulate and powdery media (7) at discrete time points. A measuring element (2) made of a chain submerged in a medium (7) or chain-shaped (2) is attached to a suspension member (5) capable of moving in the longitudinal direction of the measuring element (2) and supported by a lifting-lowering device (4) so that the actuating element (3) of the lifting-lowering device (4) cannot be moved when the suspension member (5) moves in the downward direction. The lower section of the chain (or chain-shaped) measuring element (2) extending up to the level of the medium (7) is in the medium (7), and the section above it is freely dependent on the clamping element (5). The lower portion of the measuring element (2) in the medium (7) is positioned by the medium (7), its weight is compensated by the medium (7), so it does not move in the descending direction, and the tail cannot be measured. The upper section of the measuring element (2) above the surface of the medium (7) freely hangs from the hanging member (5), so when lowered during measurement, this upper section, whose length and weight is also variable and clearly defined depending on the level of the medium (7), is defined as the weight on the hanger. (5) actuates a scales (1) placed under a suitably trained projection. The scale signal (1) indicates the level of the medium (7). After the measurement signal has appeared, the actuating element (3) lifts the upper part of the suspension element (5) and the chain or chain-shaped measuring element (2) to the upper (base) position by means of the lift-trigger device (4). <CO co CM Scope of description: Page 8, Figure 1 -1-

Description

The present invention relates to a level measuring apparatus for measuring the level of particulate, particulate and powdered media at discrete times. The mechanical submersible submerged in the medium is chain-linked or articulated and linked to a suspension element which can move in the longitudinal direction of the measuring element outside the medium to be measured. This suspension member is connected to a lifting lowering device which is not capable of exerting a thrust during lowering operation, so that the suspension member and its associated measuring member are lowered by their weight until the suspension member rests on the balance. The chain or chain-shaped measuring element extends into the medium, so that the position of its under-surface portion is determined by the medium and its weight is retained by the medium. In addition to the weight of the suspension element, only the weight of the freely-dependent section of the measuring element (medium-surface) which is directly dependent on the medium level is applied to the balance and thus the measuring signal is suitable for measuring the medium level.

Known devices for measuring the level of particulate, particulate and powdered media are diverse. Without detailing the acoustic, capacitive and radiological equipment, the mechankus equipment is also diverse. One of their groups works by measuring the height of the area above the fluid level by length measurement. The flexible suspension element of the weight released on the fluid surface drives a length measuring roller with a transmitter.

Another group of devices operating on a mechanical principle, which may be associated with the device according to the invention, determines the fluid level by means of force measurement. One example is DE 3340716 A1 (G 01 F 23/04, 23.05.1985). patent. The structure of this solution lacks a structural unit for lowering the measuring element at discrete (measuring) times, and its measuring element is equipped with floating bodies, therefore it is only suitable for measuring the level of liquid media. This is not a disadvantage of the apparatus described herein, nor is it intended to measure the level of particulate, particulate or powdered media.

The closest connection to the apparatus of the invention is provided in U.S. Patent No. 4,676,099 (G 01F 23/20, June 30, 1987). patent. The measuring element of this equipment is a twine rope. The weight of the free-hanging section of the rope above the fluid level is loaded by a lifting lowering device on the force measuring device and thus enables level measurement. It can also be used to measure other media status indicators (eg temperature) for the medium using a cable connected to the rope. According to the solution, the suspension of the rope is also specified. Namely, since the lower part of the medium is in the medium, the cable rope is subjected to a significant tensile force as the medium level decreases and tends to rotate at the point of suspension. If the possibility of rotation at the suspension point is not guaranteed, a twisting tension will also be generated in the rope. This solution allows the necessary rotation by installing a sole bearing and thus prevents significant torsional stress. The specified suspension of the rope also includes compensation for lateral (non-vertical) forces that occur when the fluid level drops. To this end, the sling ring is installed to guide the wire rope suspension point vertically or to allow the lateral forces to move with laterally sliding support. In addition to the above-mentioned solutions for the application of lateral forces, he also recommends a ball joint suspension.

The above solution also discloses a possible variant in which the suspended rope extends only to the surface of the medium. This device, in each case, recedes to the fluid level when the fluid level decreases and the increasing weight of the increasing length of the wire rope gives a signal corresponding to the decreasing fluid level. This solution already follows the principle of length measurement and solves it by means of weight measurement. The claims of the above-mentioned patent refer to the previously described variants (mounting of a sole bearing, installation of a sliding ring for vertical guiding, sliding support, ball-joint support, combining with a rope extending to the surface of the medium).

The main disadvantage of the solution detailed above is that its measuring element is a twine rope, which tends to twist under the action of stretching force during operation. If the possibility of torsion is not ensured, torsional stress is created and the filaments in contact with the rope medium are severely damaged. A disadvantage of the wire rope as a measuring element is that, during successive measurements, the length (including weight) of the freely suspended upper section loaded on the balance is not always uniformly and precisely delimited.

Because of the turbulent flow of fluid particles during descent, the stranded rope section near the fluid surface may be inclined or vertical. As a result of possible misalignment, the medium may maintain portions of different lengths of wire rope section above the surface of the medium, making it impossible to accurately measure the weight of the surface section, which in turn degrades the instrument's measurement accuracy. The greater the compression and bending stiffness of the rope, the greater the effect. This disadvantage does not occur in the embodiments of the described solution in which the rope measuring element does not extend into the medium. However, these variants have the disadvantage that the measuring equipment must be equipped with the additional components required for releasing the rope.

Considering the disadvantages of the described solution

- the tasks to be solved by the invention:

- simple, inexpensive and reliable level measuring equipment,

- increasing the accuracy of measurement.

Analyzing the closest solution to the invention described above, it can be concluded that almost all of its disadvantages (tensile stresses in its measuring element, compression and bending stiffness of its measuring element diminishes the measuring accuracy, .

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It also follows from the foregoing that only a structural element having a tensile stiffness similar to that of a rope can be used as a measuring element.

It is the inventive idea that the structural element that best suits the purpose, such as a measuring element, is a chain or a chain element of any degree of fineness.

The required tensile stiffness of the chain or chain-shaped measuring member is similar to that of a stranded rope, while there is no disadvantageous compression, bending, and bending stiffness, and no tensile stresses occur under tensile force. These features allow the measurement accuracy to be increased by incorporating it into the level measuring device as a measuring element and simplifying the structural construction of the level measuring device compared to the device most closely related to the invention (footbed, ball joint suspension can be omitted). This makes the equipment cheaper and more reliable.

The present invention thus provides a level measuring device for measuring the level of particulate, particulate and particulate media in tanks, silos, and other containers at discrete times. The submersible measuring element is a chain or chain segmented, which is connected to a suspension element, which can move in the longitudinal direction of the measuring element outside the medium. In one preferred embodiment of the invention, the lower end of the measuring element is fixed, and in another preferred embodiment, at least one guide ring is arranged around the measuring element.

The suspension member is connected to a lift-lower device which merely supports the suspension element, so that the actuator coupled to the lift-lower device cannot push the suspension element in the lowering direction. The lower portion of the measuring element extending up to the fluid surface (fluid level) is in the fluid, therefore its position is determined by the fluid or fluid surface position, its weight is balanced by the fluid, therefore it is not displaced and its weight cannot be measured. As the position of the fluid level varies (decreases or increases), the length and weight of the lower portion of the measuring element - and, consequently, of the free-hanging upper portion above the surface of the medium - is variable. In the unmeasured (basic) position of the lifting lowering device, the weight of the upper section of the weighing member rests on the suspension member and thereby on the lifting lowering device. However, in this state, particularly during descent, the lifting and lowering device may be subjected to a significant fluid pulling effect from the medium to the lower portion of the measuring element, which is more or less downward. In the case of level measurement at discrete times, the actuator allows the upper section of the gauge to sink with the help of a lifting, lowering device and suspension member, thereby placing its weight on a suitably positioned balance of the suspension member. The lowering path length must be greater than the elastic elongation of the gauge caused by the applied pulling forces prior to lowering. If this condition is not met, the balance will be subjected to the tensile force remaining after the sinking, in addition to the weight of the upper section of the measuring element, which will interfere with accurate level measurement. In the case of a measurement during a descent, the length of the lowering path shall be increased by the level of descent during the measurement. After the weighing signal emitted by the balance, the actuator lifts the upper weighing section to its (basic) position by means of a lifting-lowering device and a suspension element. The measurement time is the time between the start of the lowering and the end of the lifting.

The basic criterion for the accuracy of the measurement is that the weighing instrument only measures the weight of the upper weighing section, and possibly also the weight of the suspension member, that is, the lower weighing section cannot exert any influence on the above weight. The tensile effect that increases the gravity during measurement shall not be obtained when the upper gauge section is lowered properly, even with the use of the known twine rope gauge. However, this solution produces an upward pressure effect that reduces the weight, and is non-adjustable to varying degrees. The lower gauge section held by the medium in its variable flow position due to its flow maintains a variable length (balancing the weight of the variable length portion) of the upper gauge section due to its compression, bending and bending stiffness when selecting a rope gauge interferes with weight measurement.

The use of the chain or chain-shaped gauge according to the present invention makes it impossible to create the above disturbing condition because the girder or chain-gauge has no compression, bending, and bending stiffness. Its elements may be displaced relative to one another, rotated and displaced in the bending and deflecting directions. As a result, during lowering during measurement, the upper and lower measuring element sections are well separated for weight measurement, and the accuracy of level measurement can be significantly increased. There are other significant advantages to using a chain or chain-shaped measuring element. This has the advantage that it does not produce torsional stress due to the tensile force, so that it is unnecessary to install a sole bearing at the point of suspension. It also has the advantage that all of its elements can pivot like a ball joint at the point of attachment to the adjacent member, so that no separate ball joint is required under any circumstances. The latter two advantages help to create simple, inexpensive and reliable measuring equipment.

Also, the fixing of the measuring element at the lower end and the use of the guide ring (s) limiting the horizontal movement of the measuring element are intended to increase the measuring accuracy of the chain level measuring device by preventing the measuring element from adjusting oblique and curved. In the case of inclined and curved alignment, the length of the upper gauge section is greater than the vertical distance of the gauge suspension point from the fluid level, so the balance indicates a greater weight and a lower fluid level than the correct value.

A schematic diagram of one embodiment of the level measuring apparatus of the present invention is shown in Figure 1.

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The lower end of the measuring element 2 projecting into the container 7 is connected to the container 6 by a fastening 8. The guide ring 9 which defines the horizontal movement of the measuring element 2 is fixed to the wall of the container 6. The measuring element 2 is suspended from the surface of the medium 7 by means of a hanger 5 which is guided vertically without the possibility of turning 5. The suspension element 5 is supported by a lifting-lowering device 4 which is unable to push the suspension element 5 in the sinking direction, when it is lowered only by its own weight and the weight of the portion of the measuring element 2 10 above the surface 7 of the medium. Below the suitably designed projection of the suspension element 5, the balance 1 is placed and the actuator element 3 engages the lifting-lowering device 4. The suspension element 5, the lifting lowering device 4, the actuator 3 and the balance 1 are arranged in a weighing chamber 11, the air space of which is enclosed by a seal 10 to protect against dust contamination.

During the measurement, the actuator 3 allows the suspension element 5 to sink with the help of the lifting-lowering device 20 and with it the upper measuring element 2 above the surface of the medium 7 until it is loaded onto the balance 1 with its weight. The measuring signal emitted by the balance 1 indicates the level of the medium 7, since the level of the medium 25 7 is thus clearly defined by its length as well as by the length of the upper section of the measuring element 2. The actuator 3 then raises the suspension element 5 together with the upper section of the measuring element 2 to its upper (basic) position by means of the lowering device 4.

The technical utility of the level measuring apparatus of the invention for measuring the level of particulate, particulate and powdered media is essentially that it is simple, reliable and more accurate than prior art devices.

Claims (3)

A level measuring device for measuring the level of particulate, particulate and powdered media (7) at discrete times, the submersible measuring element (2) submerged in the medium (7) and connected to a mounting member (5) extending longitudinally of the measuring element (2). , said suspension member (5) being supported by a lifting-lowering device (4) with an actuating member (3) in an out-of-measurement condition, and a balance (1) being measured during the measurement, characterized in that the measuring member (2) submerged in the medium (7) chained. Level measuring device according to claim 1, characterized in that the lower end of the measuring element (2) submerged in the medium (7) is fixed. Level measuring device according to claim 1, characterized in that one or more guide rings (19) are arranged around the measuring element (2) immersed in the medium (7), which limits its horizontal movement.