• When installing new steam boiler systems with economisers, air preheating is the ideal solution for increasing efficiency, particularly in cases where the integration of a flue gas condenser is impractical for process reasons.
• The Bosch air preheating system is available for single or double flame tube boilers with duoblock burners. The system is economically viable from a boiler capacity of around five tonnes of steam per hour. The fan can be installed on the top of the boiler; this means that the compact system requires little space for installation. Return-on-investment (ROI) is generally achieved after 1.5 to 2 years.

In the Bosch system, a part of the heated feed water flow is utilised for increasing the temperature of the combustion air. The hereby cooled feed water increases efficiency by further reducing the flue gas temperature in the downstream economiser.

The air preheating system consists of three-way valve, a combined flue gas heat exchanger and an air-side heat exchanger. In comparison with conventional two-circuit systems, it is now possible to omit the circulation pump, the expansion vessel and various electronic safety and control systems. In turn, this reduces not only investment costs, but also the recurrent costs for maintenance and replacement parts.