Power Plant Lime Slurry Liquid Level Sensor


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chemical-feed

When this Southeast power plant needed reliable level measurement in their lime slurry mix tanks, they turned to Flowline. Lime is widely used to remove acidic gas pollutants such as sulfur dioxide from the flue exhaust streams of coal-fired electric power plants. Exhaust enters the flue from the bottom of the tower and flows upward through a dense shower of lime slurry. There, sulfur dioxide is absorbed by the lime and precipitated as wet calcium sulfite, which is often converted to gypsum and sold as a safe by-product. To begin, lime powder and water drops into the tank, raising the level from 1′ to 6′, filling the remaining air gap space with suspended dust powder. Then, the mixer turns on creating heavy agitation while the slurry is blended. Finally, the mixer turns off, the slurry is vacuum pumped out and the process starts over. Due to the presence of powder, agitation and vacuum, Flowline suggested the use of pulse radar sensors which are unaffected by such process variables. The result is reliable lime slurry level measurement. Here, an EchoPulse 6.3 GHz pulse radar level transmitter is installed on the lime slurry mix tank. The two-wire, 4-20 mA signal output is connected to the PLC for control.