Intelligent radar level gauge

working principle
Extremely short microwave pulses with low emission energy are transmitted and received through an antenna system. The propagation speed of radar waves can be regarded as the same as the speed of light, and they are converted into level signals through electronic components during the propagation process. This is the working principle of the intelligent radar level gauge!
The intelligent radar level gauge can be regarded as a special time extension tool, which ensures stable and accurate measurements in a very short period of time.
Even in complex working conditions where false echoes exist, the latest microprocessing technology and debugging software can accurately analyze the echoes of the material level.
The working principle of intelligent radar level gauge is explained from the following two aspects:
1) Input
The antenna receives reflected microwave pulses and transmits them to the electronic circuit. The microprocessor processes this signal and identifies the echoes generated by the micro pulses on the surface of the material.
The correct recognition of echo signals is completed by intelligent software, with an accuracy of up to millimeter level. 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
Since the distance E of the empty tank is known, the level L is:
L=E-D
2) Output
By inputting the empty tank height E (=zero), full tank height F (=full range), and some application parameters to set, the application parameters will automatically adapt the instrument to the measurement environment. Corresponding to 4-20mA output.
Application of 2 Intelligent Radar Level Meters
The ZYHS800 series radar level gauge is suitable for non-contact continuous measurement of the level of liquids, slurries, and particulate materials, and is suitable for large temperature and pressure changes; In situations where inert gases and volatiles are present.
The measurement method adopts microwave pulses and can operate normally within the industrial frequency range. The beam energy is low and can be installed in various metal and non-metal containers or pipelines, without causing harm to the human body and the environment.
Among them, the ZYHS800 series radar level gauge is widely used. Below is a detailed introduction to it:

Installation Guide
1) Explanation
(1) From the wall to the outer wall where the short pipe is installed: at a distance of 1/6 of the tank diameter from the tank wall, the minimum distance is 200mm.
Cannot be installed above the feeding port (4).
Cannot be installed in the center position (3). If installed in the center, multiple false echoes will be generated, and interference echoes will cause signal loss.
If the distance between the instrument and the tank wall cannot be maintained, the medium on the tank wall will adhere and cause false echoes. When debugging the instrument, false echo storage should be carried out.
2) Installation inside the tank
a、 Installation inside the tank
Within the signal beam, the following installations (1) should be avoided: such as limit switches, temperature sensors, etc. Symmetrical devices (2), such as vacuum rings, heating coils, baffles, etc. If there are (1) (2) interfering objects inside the tank, a waveguide should be used for measurement.

Best installation choice:
(1) Antenna size: The larger the antenna, the smaller the beam angle, and the weaker the interference echo.
(2) Antenna adjustment: Adjust the antenna to the optimal measurement position.
(3) Waveguide tube: A waveguide tube is used to avoid interference with echoes.
b. ZYHS801 and ZYHS802 standard installation
(1) The radar antenna cannot tilt towards the tank wall.
(2) In order to minimize the impact of temperature, spring washers must be used at the connection of the docking flange.
(3) The pole antenna must extend and install a short tube.
(4) Place the pole antenna vertically and do not direct the radar beam towards the tank wall.
c. ZYHS803 standard installation
(1) The radar antenna cannot tilt towards the tank wall.
(2) The horn antenna must extend out of the installation short tube, otherwise an antenna extension tube should be used.
(3) The horn antenna must be adjusted to be vertical, and the radar beam should not be directed towards the tank wall.
3) When the installed short tube is long, use an antenna extension tube
When the length of the horn is less than the length of the installation short tube, an antenna extension tube should be used.
If the diameter of the horn is larger than the diameter of the installation short tube, the antenna including the extension tube needs to be installed from the container and the instrument needs to be raised. Select the extension tube to raise the instrument by at least 100mm.
4) Installation inside the waveguide
The radar level gauge measures through a waveguide or bypass tube, and the measuring tube acts as a waveguide. Below is a construction diagram of a measuring tube (waveguide tube)
Construction diagram of waveguide
The inner wall of the measuring tube must be smooth, and if possible, the inner diameter of the measuring tube should match the diameter of the horn mouth. Please use longitudinally welded stainless steel tubes. The measuring tube can be extended through pre welded flanges or welded joints.
Note:
During welding, no protrusions or flanges should be produced. Align and fix the flange and measuring tube, and then weld them together. Welding should not penetrate the wall of the measuring pipe. The inner wall of the pipe must be kept smooth, and the weld and uneven areas must be carefully removed, otherwise it will cause strong false echoes.
5 Measurement conditions
1) Precautions
The measurement range starts from the point where the beam touches the lower part of the tank, but in special cases, if the tank is concave or conical, measurement cannot be carried out when the level is below this point. If the medium has a low dielectric constant and is visible at a low liquid level, it is recommended to set the zero point at a low height of C to ensure measurement accuracy. In theory, it is possible to measure the position reaching the tip of the antenna, but considering the effects of corrosion and adhesion, the final value of the measurement range should be at least 100mm away from the tip of the antenna. For overflow protection, a safe distance can be defined attached to the blind spot. The minimum measurement range is related to the antenna. With different concentrations, foam can both absorb microwave and reflect it, but it can be measured under certain conditions.
2) Actions beyond the measurement range
When the measurement range exceeds, the instrument outputs a current of 22mA.
6 Wiring methods
7 Debugging
ZYHS800 can be debugged in three ways:
JEPM (Display Adjustment Module) Debugging JESOFT (Debugging Software) Debugging HART Handheld Programmer Debugging
1) On site Programming Module (JEPM)
The JEPM programmer consists of 6 buttons and a LCD screen, which can display adjustment menus and parameter settings. Its function is equivalent to an analytical processing instrument.
JEPM debugger
2) ESOFT software debugging
Regardless of the signal output, 4... 20mA/HART, radar sensors can be debugged through software. Using BTSOFT software for instrument debugging requires a CONNECTCAT driver for the instrument.
When debugging software, power up the radar instrument with 24VDC and add a 250 ohm resistor to the front end of the HART adapter. If the instrument is powered by an integrated HART resistor (internal resistance of 250 ohms), there is no need to add an external resistor, and the HART adapter can be connected in parallel with 4... 20mA wires.
8ZYHS800 series dimensions
1) Appearance size
2) Programmer size

9. Technical data:
Basic parameters Operating frequency: 6.8GHz
Beam angle: 24 ° ZYHS801, ZYHS802
18 ° ZYHS803 with DN150 flange
14 ° ZYHS803 with DN200 flange
12 ° ZYHS803 with DN250 flange
Measurement range: 0... 35m
Repeatability: ± 3mm
Resolution: 1mm
Sampling: Echo sampling 55 times/s
Response speed:>0.2s (depending on specific usage)
Current signal: 4... 20mA
Accuracy:<0.1%
The antenna materials ZYHS801 and ZYHS802 are PP/PTFE
ZYHS803 is made of 316L stainless steel
Communication interface: HART communication protocol
Process connection ZYHS801 (PP, PTFE antenna): G1-1/2 316L stainless steel
ZYHS802 (Rod Antenna): Flanged flange DN50, DN80, DN100, DN150
ZYHS803 (horn shaped antenna): flange DN50, DN80, DN100, DN150, DN200, DN250
power supply
Power supply: 24V DC (+/-10%), ripple voltage: 1Vpp
Power consumption: max22.5mA
environmental conditions
Temperature: -40 ℃...+80 ℃
Container pressure (gauge pressure) -1... 40 bar
Explosion proof certification ExiaII C T6
Shell protection level IP68
Two wire system with shared two core wire for power supply and signal output
Cable entrance: 2 M20 × 1.5 (cable diameter 5... 9mm)

What is the difference between guided wave radar level gauge and intelligent radar?

1. Based on the on-site situation: What materials (solid, powder, liquid) were measured on site
Intelligent radar level gauges are usually used for solids and powders (such as coal mines, slag, etc.), and guided wave radar level gauges are considered for situations with large dust (such as cement plant material discharge and pneumatic conveying)
2. Liquids are usually measured using guided wave radar level gauges (such as gasoline, non corrosive chemicals in storage areas, etc.), and their dielectric constant is usually greater than 0.7, which can be measured normally. The selection of the flange for the guided wave radar level gauge is usually based on the customer's site, and a DN100 flange is normally used. Guided wave radar can be divided into pole type and cable type, and cable type radar level gauges are usually used for convenient transportation. However, for those with corrosion resistance requirements, a rod type radar level gauge (such as hydrochloric acid, sulfuric acid, etc.) can be used. For liquids with less corrosive properties, an intelligent radar level gauge can also be considered.
3. Determine whether to add heat sinks based on the temperature provided on site. For temperatures between -30 ℃ and 130 ℃, a regular type is sufficient. For temperatures above 130 ℃ and 250 ℃, I choose a radar level gauge with heat sinks. Currently, I have given up on measuring ambient temperatures above 250 ℃.
4. Select the thickness and relevant information of the flange based on the pressure parameters provided on site (see attached table). For normal pressure, there is no need to consider it.
5. Whether explosion protection is required based on the on-site environment and customer requirements, usually for chemical liquids, coal mines, etc.
If using an intelligent radar level gauge, we should be conservative in choosing speakers and try to choose larger ones to better ensure the stability of customer measurements. Here, we need to consider the dielectric constant of unfamiliar media (see attached table), which is usually greater than 2.0 without any problem. The selection of speaker size is DN150 for 0-10m, DN200 for 0-15m, and DN250 for 0-35m. For those larger than 35m, a 26G radar level gauge is required.