Because of the temperature peaks of 500 °C and higher that occur in upset operating mode, in most cases, Scheuch installs an air/air heat exchanger upstream of the bag filter for gas cooling purposes. It is critical that this system has a carefully designed control and safety concept that enables the heat exchanger to respond to upset operating mode in good time.
In heat exchangers, heat from exhaust gas is transferred to the cooling air. Air/air heat exchangers are operated in cross-flows or cross-counterflows in most cases. This is the ideal choice for dry exhaust gases. The gas to be cooled is fed into the tube interior via inlet hoods and cooled on the exterior side in cross-flow mode with ambient air supplied by axial fans. Depending on the requirements, the air/air heat exchangers are manufactured in one or multiple-stage designs that can be used on the cool-air side as well as the exhaust-air side of an installation.
Air/air heat exchangers come in a range of tube dimensions to suit the required application, and particular attention is paid to ensuring that the tube bundle has a consistent statics and temperature compensation concept.
Cooling fans are connected in groups or individually to ensure temperature control; if necessary, air/air heat exchangers can be fitted with integrated emergency cooling equipment.
Recovery of sensible heat up to approx. 100 °C
Economizers and condensers enable heat to be used in two stages; in the first stage, the ECO (economizer) recovers sensible heat on the water side at a temperature of around 100 °C. This energy can be reused between 90 and 100 °C in applications such as district heat, process heat or standard drying plants.