CN2548128Y - Amperometric material level measuring device - Google Patents

Abstract

A current method material level measuring device comprises a nylon tube 1, a branch electrode plate 5, a separating rod 6, a main electrode plate 7 and the like, wherein the main electrode plate 7 is fixed on the nylon tube 1 through the separating rod 6, a lead leading to the main electrode plate 7 enters an inner hole of the nylon tube 1 through an inner hole of the separating rod 6, and the branch electrode plate 5 is directly fixed on the nylon tube 1. The leads leading to each electrode separating plate 5 all pass through the inner hole of the nylon tube 1, the device is fixed on the container wall of the measured material by the mounting rod 3 or directly erected in the measured material pile, all the leads in the nylon tube are connected with the outside through the plug socket 4 on the container wall 2, the multipoint continuous measurement of the material height is realized, and the actual use can reach dozens of points so as to meet the requirement of the material level measurement precision. Because the resistivity difference of various materials to be measured is very large, the magnitude of the measured current can also be very large under the same measurement voltage. In order to limit the difference of total measuring current when different materials are measured, a method of adding a series resistor in a measuring power supply loop for current limiting is adopted, and the device is simple in structure, low in cost and convenient to manufacture and install. The detection circuit can complete current-voltage conversion and display driving by using only one stage of operational amplifier.

Description

Amperometric material level measuring device

Technical field

The utility model belongs to a material level measuring device, in particular to a current method material level measuring device.

Background technique

The material level measuring device is used to detect the position of the surface of the granular material, and can calculate the volume and weight of the measured material according to the obtained position data, the shape of the container, and the specific gravity of the measured material. Material level measurement is generally carried out by contacting the measuring probe with the substance to be measured. There are few types of existing material level measuring devices, and the cost is relatively high, and they are generally single-point measurement.

The existing material level measuring devices generally have complicated structure, high cost, difficult installation, and most of them are single-point measurement. If the existing material level measuring device is used to achieve multi-point measurement to meet the measurement accuracy requirements, due to the high price of the measurement probe, the use of multiple measurement probes to achieve multi-point measurement will inevitably increase the total cost significantly, and at the same time the installation workload will also increase significantly.

technical content

The purpose of the utility model is to provide a new type of material level measuring device with simple and practical circuit and measuring electrodes, low cost, convenient installation, and beneficial to realize multi-point measurement—current method material level measuring device.

The utility model is realized in this way: including nylon tube 1, installation rod 3, plug seat 4, sub-electrode plate 5, separation rod 6, main electrode plate 7, main electrode plate 7 is fixed on the nylon tube 1 through the separation rod 6, The wire leading to the main electrode plate 7 enters the inner hole of the nylon tube 1 through the inner hole of the separation rod 6, and the sub-electrode plate 5 is directly fixed on the nylon tube 1. The wires leading to each sub-electrode plate 5 pass through the inner hole of the nylon tube 1, and the device is fixed on the container wall of the measured material by the installation rod 3 or directly erected in the pile of the measured material. All the wires in the nylon tube are connected to the outside through the plug socket 4 on the container wall 2 .

The utility model also adopts the following technical solutions:

The electrode is composed of two metal sheets, the pole plates are separated by 1-10 cm, and the area of the pole plates is 10-90 cm.

There is one main electrode plate 7 and one or more sub-electrode plates 5 .

An inner hole is arranged on the nylon tube 1.

Divider bar 6 has inner hole.

The technical scheme adopted by the utility model is to apply a measuring voltage on the two pole plates separated by a certain distance. If there is a measured material between the two pole plates, a current will pass through the two pole plates, and if there is no measured material between the two pole plates, no current will pass through. The position of the material to be tested can be determined by detecting whether there is current passing through the two polar plates.

The utility model has the advantage of realizing the multi-point continuous measurement of the material height, which can be up to dozens of points in actual use, so as to meet the requirements of the measurement accuracy of the material level. Due to the great difference in the resistivity of various materials to be tested, under the same measurement voltage, the magnitude of the measured current will also have a great difference. In order to limit the difference of the total measurement current when measuring different materials, it is solved by adding a series resistance in the measurement power circuit to limit the current.

The detector of the utility model has the advantages of simple structure, low cost and convenient manufacture and installation. The detection circuit can complete the current-voltage conversion and display driving only by using one stage of op amp. The display part uses ordinary LED light-emitting diodes. Compared with various existing material level detection devices, the utility model has a high performance-price ratio. Existing various material level detection devices are often limited to single-point measurement, and to realize multi-point measurement can only use the method of accumulation of single-point measurement devices. However, the utility model is particularly suitable for multi-point measurement, which is difficult to compare with existing various material level detection devices.

Description of drawings

Accompanying drawing 1 is the structural representation of the utility model;

Accompanying drawing 2 is the schematic diagram of multi-point electrical measurement;

Accompanying drawing 3 is the use state figure of the utility model.

specific implementation

According to theory and practice, the resistivity of various materials varies greatly due to the difference in physical properties and humidity. For example, barite used in oil drilling engineering has a maximum resistivity of 2.6×10 ⁹ .m. However, the resistivity of the soil that is also used in oil drilling projects is even lower than 4×10 ⁵ .m, and the difference between the two is nearly 10,000 times. For the utility model, it must be ensured that the necessary measuring current is generated when measuring the maximum resistivity material. Since the area of the measuring electrode plate is limited by the use environment and measurement accuracy, it is impossible to make it very large. Therefore, even if a DC voltage of up to 10,000 volts is applied to the two plates, it is difficult to generate a microampere-level current when measuring high-resistivity materials. for measurement. In order to solve this problem, the measures taken are not to add DC voltage to the two plates, but to add AC voltage as the measurement voltage. Under the action of AC power supply, when there is a material to be measured between the two measuring plates, the effective value of the current between the plates is I=US/ρL√1+ω ² ρ ² ε ² (U measuring voltage effective value, ε material dielectric constant, ρ material resistivity, S electrode plate area, L distance between two plates). It can be seen from this formula that under the condition that all parameters remain unchanged, the measurement current is related to the frequency, and as the frequency increases, the measurement current will increase accordingly. According to the experiment, using a 50Hz power frequency power supply as the measurement power supply can meet the requirements of measuring the material with the largest resistivity.

When there is material in the middle of the detector composed of bipolar plates, the current flowing through it is converted into a voltage signal by a current-voltage converter composed of an operational amplifier. The voltage signal can directly drive the LED light emitting diode. In this way, when there is material in the detector, there is current passing through, and the light-emitting diode is on; when there is no material in the middle of the detector, there is no current passing, and the light-emitting diode is off. In the material level detection device composed of multi-point detectors, the height or position of the measured material can be determined by the status of the light-emitting diodes that have been lit and the conditions of the non-light-emitting diodes.

Figure 1 illustrates the construction of a multipoint detector. The multipoint detector consists of a main electrode plate 7 and a plurality of partial electrode plates 5 . The main electrode plate 7 is fixed on the nylon tube 1 through the insulating plastic separating rod 6 , and the wire leading to the main electrode plate 7 enters the inner hole of the nylon tube 1 through the inner hole of the separating rod 6 . Each sub-electrode plate 5 is directly fixed on the nylon tube 1 . The wires leading to each sub-electrode plate 5 pass through the inner hole of the nylon tube 1 . The multi-point detector is fixed on the container wall 2 of the material to be tested by the installation rod 3 or directly erected in the pile of the material to be tested. All the wires in the nylon tube 1 are connected to the outside through the socket 4 on the container wall 2 .

Accompanying drawing 2 is the electrical schematic diagram of multi-point detection. The multi-point detection circuit is actually a combination of single-point detection circuits. The difference is that the multi-point detection circuit shares an isolation transformer, a current limiting resistor, and a plate of the detector --- the main electrode, and T is an isolation transformer. , R1 is the current-limiting resistor, the operational amplifier A forms the current-voltage converter, R _f is the feedback resistor, _R2 is the output current-limiting resistor, and LED is a light-emitting diode.

According to the needs, install and fix the single-point or multi-point detector on the place where the tested material is piled up or on the container wall of the tested material. When the power is detected, if there is a material to be tested between the two poles of a certain detector, a current flows through the detector, and the current signal is converted into a voltage signal by a current-voltage converter, and the LED light-emitting diode of the load is driven to emit light, indicating the corresponding Material exists at the location or height. If there is no material to be tested between the two pole pieces of a certain detector, no current flows through the detector, the input current of the current-voltage converter of the subsequent stage is zero, and the output voltage is also zero, and the load LED light-emitting diode is off, indicating the corresponding position Or highly no material exists.

As shown in Figure 3, the amperometric material level detection device is composed of a measuring electrode, a power supply, a current-voltage converter and a display device LED light-emitting diode. The measuring electrode is composed of two metal sheets separated by several centimeters and the plate area is about tens of centimeters. The specific values of the gap between the two plates and the area of the plates can be determined by the resistivity of the material to be measured, but the plate area of 30cm ² and the electrode spacing of 3cm can meet the requirements of measuring any resistivity material. The measurement power supply is provided by an ordinary 50Hz power frequency power supply after being isolated by an isolation transformer. When testing, if there is a material to be tested between the two pole pieces of a certain detector, under the action of the measuring power supply, a current flows through the detector, and the current is converted into a voltage signal by the current-voltage converter of the subsequent stage circuit and drives the LED. The light-emitting diode emits light to indicate the position or height at which the measured material reaches the detector. If there is no material to be tested between the two poles of a detector, no current flows through the detector, and the output voltage of the current-voltage converter of the subsequent stage circuit is zero, and the LED light-emitting diode of the display device does not emit light, indicating that the material to be tested has not reached the detector. The position or height at which the detector is located. The current method material level detection device can use single-point detection or multi-point detection according to needs to meet the requirements of measurement accuracy.

The utility model is characterized in that a sinusoidal measuring voltage is applied to two pole pieces separated by a certain gap to detect whether there is a current passing through the two pole pieces, so as to determine whether there is a measured material between the two pole pieces to detect the position or height of the measured material.

Adopting this circuit is a specific means to realize the current method to detect the material level. At the same time, the circuit not only completes the current-voltage conversion of the measured current, but also completes the driving of the subsequent LED light-emitting diodes. The circuit output voltage V _o is determined by the formula V _o =I _i ×R _f , where I _i is the detection current, and R _f is the feedback resistance. In the circuit, D ₁ and D ₂ are protection diodes of operational amplifiers, and R ₂ is a current-limiting resistor.

The isolation transformer T is used to provide a detection power independent of the earth for the detection circuit of the subsequent stage, so as to ensure the safe and reliable operation of the detection device. The primary and secondary voltage ratio of the isolation transformer is 1, that is, the input and output voltages of the isolation transformer T are equal. The value of the current limiting resistor _R1 is not less than the ratio of the output voltage of the isolation transformer T to the maximum output current.

Claims (5)

1. Current method material level measuring device, including nylon tube (1), installation rod (3), plug seat (4), sub-electrode plate (5), separation rod (6), main electrode plate (7), its characteristics That is: the main electrode plate (7) is fixed on the nylon tube (1) through the separation rod (6), and the wire leading to the main electrode plate (7) enters the inner hole of the nylon tube (1) through the inner hole of the separation rod (6), The sub-electrode plate (5) is directly fixed on the nylon tube (1), and the wires leading to each sub-electrode plate (5) pass through the inner hole of the nylon tube (1). The device is fixed on the material to be tested by the installation rod (3). All wires in the nylon tube (1) are connected to the outside through the socket (4) on the container wall (2). 2. The current method material level measuring device according to claim 1, characterized in that: the electrode is composed of two metal sheets, the plates are separated by 1-10 cm, and the area of the plates is 10-90 cm. 3. The amperometric material level measuring device according to claim 1, characterized in that there is one main electrode plate (7) and more than one sub-electrode plate (5). 4. The current method material level measuring device according to claim 1, characterized in that: the nylon tube (1) has an inner hole. 5. The current method material level measuring device according to claim 1, characterized in that: there is an inner hole on the separating rod (6).

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