There are two main purposes of material level measurement: first, to determine the quantity of materials in the container through material vibrating fork level measurement to ensure the continuous supply of materials required in all stages of production; The second is to know whether the material level is within the specified range through material level measurement, so as to ensure the normal production process and ensure the product quality, output and production safety. There are many kinds of instruments for level measurement, such as radio frequency admittance level switch, vibrating bar level switch, tuning fork level switch, anti-rotation level switch and radar level meter. This paper mainly introduces the radar level gauge and its working principle.

1、 Overview of radar level gauge

The radar level meter adopts HART communication protocol, which can be configured by computer and handheld communicator, and can adjust parameters and judge faults through instrument measurement and echo curve. It is composed of transmitting and detecting devices, and uses the special performance of electromagnetic wave to detect the material level. The transmitter of the radar level gauge can emit a special electromagnetic wave. The physical characteristics of the electromagnetic wave are similar to that of visible light, and it travels at the speed of light, and the propagation speed is not affected by the characteristics of temperature, pressure, steam and other media. The emissivity of the radar level gauge depends on the conductivity and dielectric constant of the measured medium. The electromagnetic wave can penetrate the space nitrogen, dust and other interference sources. It is easy to be reflected when encountering obstacles. The better the conductivity of the measured medium or the greater the dielectric constant, the better the reflection effect of the echo signal.

Because the radar level meter adopts advanced echo processing and data processing technology, and the radar wave itself has high frequency and good penetration performance, the performance of the radar level meter is better than that of the contact level meter and the similar non-contact level meter. Specifically, the radar level meter has the following characteristics and advantages: ① It has a wide range of English-Chinese translation and can measure almost all media. ② Simple operation and maintenance, convenient debugging. ③ Safety and environmental protection, accurate measurement and strong reliability. ④ Continuous and accurate measurement under adverse conditions

2、 Working principle and measuring process of radar level gauge

1. Working principle of radar level gauge

The measuring principle of radar level gauge is based on the principle of time travel, and it works in the way of transmitting, reflecting and receiving. The transmitting device sends out high-frequency pulse and propagates along the detection component (steel cable or steel bar). When the pulse encounters the material surface, it is reflected back and received by the receiver in the instrument. The distance is calculated according to the proportional relationship between the distance and the pulse time, and the distance signal is converted into a material level signal through electronic components.

2. Measurement process of radar level gauge

(1) The transmitter sends out high-frequency pulse and propagates along the detection component (steel cable or steel bar). The reflected pulse signal is transmitted to the instrument electronic circuit along the cable. The microprocessor processes the signal to identify the echo generated by the microwave pulse on the material surface. The correct echo signal recognition is completed by intelligent software. The distance D from the material surface is proportional to the time travel T of the pulse: D=CXT/2, where C is the speed of light.

As shown in the figure, since the distance E of the empty tank is known, the material level L is: L=E-D

(2) Set by inputting empty tank height E (zero point), full tank height F (full range) and some application parameters, which will automatically adapt the instrument to the measurement environment. The microprocessor inside the radar level meter converts the material level into 4~20mA electrical signal output.

Kaidi KD-R series radar level/material level meter is a special level/material level meter with a measuring range of 30m. The 25GHz high-frequency pulse of the horn antenna is especially suitable for applications with high dust and high temperature materials. The product adopts a unique collimator (universal joint) design, which can adjust the launch angle of the antenna according to the field working conditions, so as to effectively improve the reliability of the tilt solid material measurement.