Once the bottom part of the checkers is clean, we can start the cleaning of the top part by blowing compressed air (air pressure: 12 bars; flow rate: 11,5 m³/min). As the bottom of the checkers is clear, all the material blocking the top part can fall all the way down to the floor. Since it’s impossible to get inside this part of the chamber, we use some water cooled lances ( from 5 to 7 meters long; external diameter 65 mm; diameter of the blowing hole: 10 mm) to blow the air inside each chimney.