In the exhaust gas pipe of the CHP, a t- piece is used after the sound absorber. A dual effect, failsafe exhaust flap installed there, guides the hot exhaust gas through a stainless pipe to the dryer. This mixes the approximately 550°C (1022°F) exhaust gasses to the desired dryer input temperature of 300°C (572°F).
If the exhaust gas energy of the biogas powered CHP is not sufficient to dry out the desired sewage sludge amount, an additional combustion chamber can be incorporated into the exhaust gas flow with a natural gas burner. The missing energy will be calculated by the process computer and the additional heat is supplied by the natural gas burner.
The hot exhaust gases are divided symmetrically into the individual drying chambers. Several temperature sensors monitor the process continually. The required mixed air volume is calculated continually and added to the exhaust gas flow. When the drying process begins, the failsafe valve is opened and hot exhaust gas is fed into the dryer. When the drying procedure ends, the exhaust gas valve closes the path to the dryer and the exhaust gases are conveyed through the normal exhaust system of the CHP into the atmosphere.