Application: Fly ash is captured and removed from the flue gas by electrostatic precipitators or fabric bag filters located at the outlet of the furnace and before the induced draft fan. The fly ash is collected in hoppers below the precipitators or bag filters and periodically removed from them.
Challenges: ESP hoppers are continuously filled with hot fly ash. The combined effect of humidity and temperature cause the fly ash to stick to the sides of the hopper. This can cause material build-up and clogging of the hopper which in turn can damage the ESP plates.
Continuously monitoring and understanding the distribution of fly ash in the hoppers is extremely important for end-users. With accurate real-time information at hand, preventative action can be taken to empty the hoppers on time, and to clean and perform maintenance work if and when necessary. This is essential in order to prevent clogging-up and risks of damage to the ESP plates. Damaged plates can create environmental and health concerns as well. The APM technology is the only presently available technology that permits continuous volume level measurement of fly ash inside an ESP hopper. The 3DLevelScanner’s 3D visualization tool allows the end-user to see the actual allocation of material inside the hopper and detect build-ups as they occur, facilitating the scheduling of timely maintenance to avoid unexpected and costly interruptions of the process, and damage to the ESP plates.
At coal-fired power plants where APM’s scanning technology is not used in ESP processes, the emptying of the hopper is disconnected from the filling. There is no reliable way to measure the amount of fly ash in the hopper so a timer is set to turn on the emptying regardless of the amount of fly ash remaining in the hopper, making the whole process very inefficient, and causing, for example, the air compressors to work unnecessarily. The APM scanner allows users to reliably coordinate and automate the filling and emptying of these hoppers.