Coal bunkers
Level measurement
Hard coal and brown coal are the main energy sources for a coal-fired power plant. Delivered by ship or train, the coal is unloaded into bunkers up to 30 m high. The coal is transported to these bunkers from stockpiles at the power plant via conveyer belt systems either over ground or underground. Additional conveyor belts feed pulverizations units where the coal is converted into a fine dust for subsequent combustion in the boiler firebox.
Reliable level measurements are necessary to guarantee uninterrupted feeding of the firebox and prevent overfilling in the bunkers.
A simple solution for this application is setup of a radar sensor at the top of the bunker for no-contact level measurement due to dust and a 2-wire capacitive measurement sensor to prevent overfilling. Since this application is critical, extra alarms are required. Using the PR 4116 universal transmitter combined with the PR 4510 display / programming front, alarms can be activated in case of overfilling and the latching relay function will stop the feeding belt if an overfill condition is detected.
Application:
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What signal conditioning challenges are unique to coal bunker level measurement?
Coal bunker environments present heavy dust, extreme temperature variations (from ambient to self-heating coal at over 100 degC), and strong electromagnetic interference from nearby coal handling conveyors and motor drives. Level transmitter signals can be corrupted by ground loops between the bunker structure and the control room, often located hundreds of meters away. PR Electronics isolators with greater than 60 dB signal-to-noise ratio and 2.3-2.6 kVAC galvanic isolation overcome these challenges, delivering reliable level data to the combustion control system.
