Application of Vibrating Rod Level Switch in Carbon Black Level Measurement

Carbon black is a kind of fine, light and loose powder, which is widely used as raw material of ink and paint, and also used as tire reinforcement medium to extend tire service life.

In the production process, the density of carbon black is low (0.032 to 0.048g/cm³). Carbon black has strong adsorption effect, and the internal temperature of some carbon black collecting containers are over 200℃. Above special working conditions make the accurate level measurement difficult to achieve, and hard in maintenance. On the other hand, once level switch occurs false alarm, it is easy for carbon black to overflow and pollute the environment. In addition, the level state of carbon black is a significant parameter for granulation process, which directly affects the granulation quality. Thus, to select a reliable level switch is crucial.

Various of level instruments are being used to measure powder level, such as rotary paddle switch, capacitance level switch, RF admittance level switch, vibrating level switch, etc. However, only vibrating rod level switch can measure carbon black level reliably.

According to the different probe structure, vibrating rod level switch can be divided into single rod and double tube nested inside and outside. The working principle is to drive the probe to vibrate through piezoelectric ceramics, and output an alarm signal by detecting the change of probe frequency and amplitude value when touches the medium. For single rod structure, there is no resonant state, so the probe is completely driven by piezoelectric ceramic. Besides, due to the low-density and strong adsorption ability of carbon black, the anti-hanging ability of single rod level switch is poor. On contrary, Tube-11 Vibrating Rod Level Switch is designed with double vibration tubes. The inner vibration tube nests with the outer vibration tube. When the resonant frequency of inner and outer vibrating tubes is finely adjusted to the same value, both the reliability and the sensitivity of the vibrating rod level switch are very high. Therefore, the measurable medium density can be as low as 0.02 g/cm³. Also, Tube-011 is an industry leading product that can tolerate high process temperature up to 250℃, and ultra-high temperature up to 400℃(Water/air cooling).