Selection of sewage level gauge

Selection of sewage level gauge-Jiangsu Dingsheng Instrument Co., Ltd

Liquid level gauge in sewage treatmentIt accounts for a large proportion in applications and is almost used in every aspect of sewage treatment. In sewage treatment, it is necessary to measure the liquid level of wastewater and sludgeChemical solutions, etc. In sewage treatment systems using automatic control, liquid level gauges are not only used to measure liquid levels, but also involve the start and stop of interlock pumps and the opening and closing of control valves in automatic control. Therefore, the appropriate selection of liquid level gauges plays a very important role in achieving the requirements of production processes in a reasonable manner.

1、 Magnetic flap level gauge:

Measurement of sewage principle: The liquid level gauge works based on the principles of buoyancy and magnetic coupling. When the liquid level in the tested container rises or falls, the float in the main tube of the level gauge also rises or falls accordingly. The magnetic steel inside the float is transmitted to the on-site indicator through magnetic coupling, driving the red and white flip columns to flip 180 °. When the liquid level rises, the flip column changes from white to red, and when the liquid level drops, it changes from red to white. The red and white boundary of the indicator is the actual height of the medium liquid level in the container, thus achieving the indication of the liquid level.

Features:

(1) Simple structure, clear display, intuitive reading, especially suitable for on-site display.

(2) The equipment has few openings, so magnetic flap level gauges with remote output are generally used to monitor both on-site and remotely

(3) According to the condition of the medium, such as easily contaminated and blocked media, it is necessary to regularly clean the main pipe and remove the sediment inside the pipeline to ensure the accuracy of the measurement.

In sewage treatment processes, magnetic flap level gauges are commonly used for measuring liquid levels in chemical solvent tanks, acid tanks, alkali tanks, and other tanks

2、 Ultrasonic level gauge:

Ultrasonic level gauge uses the principle of ultrasonic reflection at the liquid level to detect liquid level deviation, that is, it works by applying the principle of echo measurement distance. When the ultrasonic probe emits short ultrasonic pulses towards the liquid surface, after a time t, the probe receives echo pulses reflected back from the liquid surface. Therefore, the distance between the probe and the liquid surface can be calculated according to the following formula: assuming the distance from the ultrasonic probe to the bottom of the container is h, the actual liquid level. In the equation, v is the speed at which ultrasonic waves propagate in the measured medium (i.e., the speed of sound m/s). Therefore, it can be seen that as long as the speed of sound v is known, it can be passed throughaccurateMeasure time t and determine the height H of the liquid level

Features:

(1) Ultrasonic level gauges can achieve non-contact measurement, with stable and reliable operation: Ultrasonic level gauges are installed above material silos and tanks, without direct contact with materials, overcoming the drawbacks of other models of level gauges that directly contact materials.

(2) The measurement range is large, and liquid, block, and powder levels can be measured.

(3) It can measure continuously at fixed points and conveniently provide telemetry and remote control measurement signals.

(4) Installation is simple and convenient, and no safety protection is required.

Disadvantages:

(1) Ultrasonic level gauge measurement may have blind spots, which need to be avoided during installation. When the liquid level enters the blind spot, the ultrasonic transmitter cannot measure the liquid level. Therefore, when determining the range of the ultrasonic level gauge, a margin for the blind spot must be left, and the transmitter probe must be higher during installationZ高Left and right of the liquid level blind zone. This is the only way to ensure accurate monitoring of the liquid level and ensure the safety of the ultrasonic level gauge.

(2) When there is foam in the ultrasonic level gauge, because the sound wave cannot penetrate the foam, the sound wave will be reflected back on the foam, so the measurement will have a large deviation from the actual liquid level. Defoamer can be added to the tank container with foam to reduce the production of foam and ensure accurate measurement.

(3) Ultrasonic level gauges in containers with agitators are affected by the agitators, resulting in false reflections and inaccurate measurements. By reducing the speed of the mixer and installing the level gauge away from the center of the mixer, the influence of the mixer on the measurement of the ultrasonic level gauge can be reduced.

(4) The temperature of the measuring medium also has an impact on the ultrasonic level gauge, especially in a closed container. When there is a temperature difference between the medium and the surrounding temperature, water droplets will condense around the probe, which will affect the accuracy of the measurement. When installing the ultrasonic level gauge, it is possible to reduce the impact of water droplets condensed due to the temperature difference between the medium, container, and probe on the measurement by blowing compressed air pipe towards the probe.

3、 Radar level gauge:

The antenna of a radar sensor emits electromagnetic wave signals in the form of a beam, which reflects off the surface of the measured material. The reflected echo signal is still received by the antenna. Each point in the emitted and reflected beams is collected using ultrasonic sampling method. The signal is processed by an intelligent processor to obtain the distance between the medium and the probe, and sent to the terminal display for display, alarm, operation, etc. The distance D from the surface of the material is proportional to the time travel T of the pulse:

D=C×T/2

Where C is the speed of light and the distance E from the empty can is known, then the level L is: L=E-D

Characteristics of radar level gauge:

(1) The radar level gauge adopts an integrated design, with no movable parts, no mechanical wear, and a long service life.

(2) Due to the characteristics of electromagnetic waves, they are not affected by the environment. Therefore, its measurement has a wide range of applications. The probe of the radar level gauge is non-contact with the surface of the medium, which belongs to non-contact measurement and can accurately and quickly measure different media. The probe is almost unaffected by temperature, pressure, gas, and other factors. It can be used in occasions where the working conditions are bad, the changes are large, and the ultrasonic level gauges such as moisture, steam, foam are not competent.

(3) Radar level gauges are also suitableUsed in situations where there is a mixer and the liquid level is constantly changing.

(4) Radar level gauges are relatively expensive, but they can be applied to almost all liquid level control processes in wastewater treatment.

On site working condition diagram of Dingsheng Instrument (intelligent radar level gauge):

1. Ruida Petroleum

2Henan Xing'an Power Plant

3. Qinling Cement

4. Western Union Thermal Power Plant

5. Xinjiang Huaneng Iron and Steel Plant

6newXinjiang Qinghua Coal Mine

7. Extend oil

4Selection of sewage level gaugeSummary:

In summary, due to the many occasions where liquid level measurement is required in the process of sewage treatment, as well as the characteristics of the sewage treatment process itself, in the selection process, it is necessary to select suitable liquid level gauges based on the characteristics of each process and medium. This will have a significant impact on the accuracy, reliability, stability, and economic service life of the process measurement. It is recommended to choose liquid level gauges with high accuracy, minimal maintenance, and long lifespan as much as possible, subject to budget constraints. Ensure that the liquid level measurement and control of the entire sewage treatment system operate reliably, stably, and safely.