To meet the emission standards for fly ash and flue gas generated by coal combustion, a large distillery added pulse bag filters during its technological transformation. The key feature of these filters is using high-pressure air to blow dust off the filter bags via pulse valves, collecting the dust in the hopper below. A level switch is employed to detect the fly ash level inside the hopper; when the level reaches a high point, it sends an alarm signal to prompt timely emptying of the hopper.
After long-term coal combustion, the cinders are discharged from another outlet, while the flue gas is filtered through the bag filter to form fly ash. The characteristics of this fly ash after high-temperature combustion are as follows: first, it has a relatively high temperature, up to about 200°C; second, it is completely powdery after filtration by the bag filter. Due to the high temperature, it has low humidity and is relatively dry, with a very stable dielectric constant.
The customer initially chose rotary paddle level switches. Although these switches can withstand the required temperature, their working principle relies on a micro-motor as the driving device, connected to the transmission shaft via a clutch and driven by the motor—making them mechanical in nature. Their protection level generally only reaches IP65. When measuring powdery fly ash, fine dust can easily enter the switch over time if the protection level is insufficient, leading to jamming and false alarms.
Based on the on-site working conditions and the characteristics of fly ash, we recommended the customer adopt our NYSP-UK universal RF admittance level switch.
