Shandong Weifang Xinte ultrasonic flowmeter is selected for sewage measurement in urban sewage treatment plants, pharmaceutical factories, and paper mills

In order to improve the increasingly serious water pollution situation, many cities have established sewage treatment plants, significantly increasing the sewage treatment rate and gradually improving the water environment. With the rapid development and popularization of computer technology, data collection systems have also been rapidly applied. The application of this system in the production process can collect, monitor, and record process parameters on the production site, providing information and means to improve product quality and reduce costs. Data collection is the process of collecting analog signals output by sensors, converting them into digital signals that can be recognized by computers, and then further processing them.

Ultrasonic flowmeter is an instrument that measures flow by detecting the effect of fluid flow on ultrasonic pulses. Like electromagnetic flow meters, it is an unobstructed flow meter due to the absence of any obstacles in the instrument flow channel. It is a type of flow meter suitable for solving the problem of difficult flow measurement, especially in the measurement of large caliber flow. It is also one of the rapidly developing flow meters in recent years.

Principle of Ultrasonic Flow Meter

compose

The non-contact ultrasonic measurement system consists of two parts: an ultrasonic signal transducer and a remotely mounted electronic transmitter/receiver. The transducer continuously emits a series of ultrasonic waves and receives reflected echoes from the surface of the detected liquid or solid. The microprocessor in the transmitter further processes the signal and displays the data as LCD digital display.

(1) Sound waves are a type of mechanical wave with a frequency exceeding 2 × 10⁴ Hz sound waves are ultrasonic frequencies that are inaudible to the human ear. The relationship between its wavelength L, frequency f, and velocity c is

L=c/f

(2) Reflection and Refraction of Ultrasonic Waves

When sound waves propagate to the interface between two media, some of the energy can return to the original medium, called reflected waves, while the other part of the energy passes through the surface of the medium and continues to propagate inside the other surface, called refracted waves.

反射定律： Sina/ Sina'＝＝C₁/C₂

In the formula, the incident angle a and the incident wave velocity C₁Reflection angle a ', reflection wave velocity C₂.

Refraction law: SINa/SINb==C₁/C₂

In the formula, the incident angle a, the refractive angle b, and C₁For the wave velocity of the medium, C₂The second medium wave velocity.

Characteristics of Ultrasonic Flow Meter

The prominent feature of ultrasound is its high frequency, resulting in shorter wavelength, smaller diffraction phenomenon, and better directionality. It can be called radiation and propagate directionally. Low attenuation and high penetration ability in liquids and solids, significant reflection occurs when encountering impurities or interfaces. Ultrasonic sensors are widely used in many scientific fields, including industrial production, by utilizing these significant characteristics of ultrasound.

Ultrasonic transducer

Ultrasonic transducer, also known as ultrasonic probe, is a device that converts electrical energy and acoustic energy into each other. In ultrasonic testing technology, an instrument device that emits and receives ultrasonic waves and converts them back into electrical signals is called an ultrasonic transducer or probe. There are various types of ultrasonic transducers used for testing, such as piezoelectric, magnetostrictive, electromagnetic, vibrating plate, elastic surface wave, and so on. In detection technology, piezoelectric type is mainly used.

Advantages and disadvantages analysis

Advantages:

◆ Can be used for non-contact measurement;
◆ For measurement without flow obstruction and pressure loss;
◆ It can measure non-conductive liquids and is a supplement to electromagnetic flow meters for unobstructed measurement.
The biggest advantage of ultrasonic flow level is that it can perform unobstructed flow measurement without cutting off the pipeline, making it a truly non-contact flow instrument.

Disadvantages:

The transmission time can only be used for cleaning liquids and gases; The Doppler method can only be used to measure liquids containing quantitative suspended particles and bubbles;
The Doppler method has low measurement accuracy.

application

Ultrasonic measurement is a method of measuring container storage by determining the level of the material. The ultrasonic sensor sends ultrasonic pulses from above to the surface of the material and receives the echo reflected back from the surface. It measures the propagation time of ultrasonic waves and calculates the distance from the reflecting surface.

The propagation time is an intuitive dimension of the distance between the ultrasonic sensor and the object level. The propagation distance of sound waves is the product of propagation time and sound velocity. If the location of the ultrasonic sensor is known, then the level (and storage) can be converted. The range of sound velocity variation in the air is large, therefore, acoustic sensors need to be temperature compensated. If used for gases other than air, corresponding calibration should be carried out.

measure traffic

In the flow measurement instruments of sewage treatment plants, there are only two types of flow meters classified by installation form: pipeline type and open channel type.

Open channel ultrasonic flowmeter is a widely used flowmeter in sewage treatment plants. Therefore, we will only briefly explain the open channel flowmeter here. The flow rate of liquid in an open channel has a definite relationship with the liquid level at a certain point on the tank, that is:

Q＝Kbhm

In the formula, Q is the flow rate, K is the flow coefficient, b is the width of the weir, h is the liquid level height, and m is the index.

For a certain shape of water tank, the values of k, b, and m are constant, so as long as the liquid level h is measured, the flow rate can be calculated. From this, it can be seen that the ultrasonic flowmeter used for open channel flow measurement is actually measuring the liquid level.

Measure liquid level

Ultrasonic level gauges have been widely used in sewage treatment plants due to their non-contact measurement, high accuracy, and low maintenance requirements.