1 Introduction
After the deep desilicated sodium aluminate solution is pumped by the semen to the buffer tank, the discharge valve adjusts the flow rate and enters the carbon separator tank for continuous carbonation decomposition. The carbon separation tank is divided into two groups, the east and the west, and each group has 6 tanks. In order to make the continuous decomposition more thorough, the slurry level must be measured accurately. However, the on-site environment is harsh, and the amount of steam is very large. Traditionally, the traditional method of rope testing has been used. Not only is the measurement result inaccurate, but it also poses a great safety hazard for operators.
2 radar level gauge application
The long-term instrumentation company's latest research on radar level gauges is aimed at specific applications such as tanks, buffer tanks and process tanks as well as radar detection in high temperature, high pressure, inert gas coverage or steam applications. Since 1999, our plant has adopted radar level gauges in the carbon separation process, which not only brings great convenience to operators, but also provides accurate and favorable measurement data for alumina process monitoring. The following is an analysis of the working principle and performance characteristics of radar level gauges.
2.1 The working principle of radar level gauge
The horn antenna of the radar level gauge emits short microwave pulses to the measured object (measurement medium) and is reflected by the surface of the medium. The distance from the microwave pulse to the surface of the medium is proportional to its travel time D = C × T/ 2 . D: distance from the sensor to the surface of the medium C: microwave wave speed T: travel time By entering the empty tank distance E, full tank distance F and an application parameter A, the radar level gauge can be calibrated to automatically adjust the instrument to the measurement state. See Figure 1 below. The unit of measurement is based on the type of antenna, the conditions inside the tank, and the measured medium. It is measured in m at our factory. 
Figure 1 radar level gauge working principle diagram
2 . 2 Structural features
Radar level gauge structure shown in Figure 2.
FHV160 operation and display module --- wiring cavity --- signal transmission unit In the figure: FHV160 operation and display module for parameter setting and data display; wiring cavity to provide power and liquid level signal to the instrument, signal transmission unit will The level signal becomes a 4 to 20 mA current signal.
2. 3 radar level gauge installation and debugging
The microwave must reach the surface of the boundary material without interference and generate an echo in order to accurately reflect the status of the liquid level. Radar level gauges are mounted on an add-on pipe via a flange. In order to obtain a strong echo signal, the instrument should be installed at least 30cm away from the tank wall, but not in the center of the tank. At the center or obstruction, the microwave beam has as few components as possible. During the inspection, the two pins on the flange should be parallel to the tank wall, and the horn is perpendicular to the surface of the medium. The power cable and signal cable connected to the electronic cavity are independent and must use two-wire shielded cables. As shown in Figure 3. 
Figure 3 level gauge installation diagram
2. 4 parameter settings and performance characteristics
The parameter setting is through a 10 × 10 matrix. The matrix can be locked to prevent unauthorized input. On the FHV160 operation panel, use the keys V, H to select the matrix area, key + - → input parameters, E to confirm, press + - to change the decimal point, → to change the number. Table 1 shows the main application parameters. More code acquisition can be achieved by pressing the + - key. The minimum level corresponds to the 4mA signal, and the highest level corresponds to the 20mA signal, and they are linearly related to each other.
Table 1 parameter setting table
Parameter H0 H1 H2 H5 H6 H9
V0 Empty Mark (E) Full Mark (F) 4mA Corresponding Value 20mA Corresponding Value Measurement Value
V9 fault code
2.5 Advantages
(1) Safer and more intuitive;
(2) Corrosion and wear resistance;
(3) Less maintenance;
(4) Display of measurement data is straightforward and accurate and continuous;
(5) In the fault code, it is convenient to find out what the fault is.
2.6 Failure Analysis
(1) The measured value is incorrect. One reason is that there is an error in the D calibration. Check E and F. If necessary, type in a new application parameter in V0H3. Reason 2 is 4mA. 20mA sets the corresponding value to be incorrect.
(2) No current output, one of which is to insert the wrong slot; the other is that the wiring is incorrect or the line is open; the third is no power output or no current supply;
(3) Occasional loss of wave, indicating no movement, for one reason to clean up the antenna; the second reason is that the horn antenna is parallel to the wall of the tube.
3 Conclusion
The application of radar level gauges on the carbon slot is feasible, but there are still deficiencies in the analysis from the failure, and it needs continuous improvement.
Topwell Crafts Co., Ltd , https://www.topwellmetal.com