Waste water discharged from polluted
sources, because of its high total amount or concentration of pollutants, which
cannot meet the requirements of discharge standards or environmental capacity so
as to reduce the quality of water environment and functional objectives. This
place which must be strengthened manually is a sewage treatment plant, also
known as a sewage treatment station.
With the rapid development of China's
economy and the increase of industrialization, the pollution of water resources
is also aggravating, especially the increasing discharges of urban sewage and
industrial sewage, which result in increasingly serious water pollution. The country
pays more and more attention to the protection of water resources, and
strengthens the treatment of urban sewage and industrial sewage. It puts
forward higher requirements for achieving the best effect of various sewage
treatment processes, normal operation of treatment equipment, accurate
monitoring of water quality and quantity of sewage treatment. In this situation,
the life and industrial sewage treatment process is also constantly improving.
Many cities have established sewage treatment plants.
The sewage treatment rate
has increased significantly, and the environment of the water has gradually
improved. With the rapid development and popularization of computer technology,
data acquisition system has been rapidly used. This system can be used to
collect, monitor and record the process parameters on the production site, and
provide information and means for improving product quality and reducing cost.Data
acquisition is to collect analog signals from sensors and convert them into
digital signals recognized by computers for further processing.
Nowadays, with the development of digital liquid measuring device
various types of liquid level meters have appeared. There are glass plate level
gauges made by the principle of connectors, magnetic flip plate level gauges
made by adding magnetic floats through the principle of magnetic coupling, liquid
level transmitters for measuring liquid differential pressure, ultrasonic flow
level gauges made by the principle of ultrasonic reflection and so on. This article
introduces the method of liquid level measurement by ultrasonic pressure sensor for liquid level in sewage
In the process of sewage treatment, the
ultrasonic pressure sensor for liquid
is used to detect the liquid level deviation by the reflection
principle of ultrasound at the liquid level, that is, the echo measuring
distance principle. When the ultrasonic probe emits a short ultrasonic pulse to
the liquid surface, after time T, the probe receives the echo pulse reflected
back from the liquid surface. Therefore, the distance from the probe to the
liquid surface can be calculated by the following formula: the distance from
the ultrasonic probe to the bottom of the container is h, the actual liquid
level will be determined. In the formula, V is the velocity of ultrasonic wave
propagating in the medium under test (i.e. the velocity of sound m/s).
shown that the liquid level H can be calculated by measuring the time accurately as long as the velocity of sound V is known.
It can be seen that ultrasonic measurement
is a method to measure the storage of containers by measuring the material
level. The ultrasonic sensor transmits the ultrasonic pulse from the material
surface and receives the echo reflected from the surface. It measures the
propagation time of ultrasound and calculates the distance from the reflecting
surface. The propagation time is the direct dimension of the distance between
the ultrasonic sensor and the level. The propagation distance of sound wave is
the product of propagation time and sound velocity. If the location of the
ultrasonic sensor is known, then the level (and reserves) can be calculated. Sound
velocity varies widely in the air. Therefore, the acoustic sensor needs
temperature compensation. If it is used in other gases besides air, it should
be calibrated accordingly.