Excess heat is unavoidable in thermal processes. Depending on the efficiency of the process, the loss of heat can be up to 60 percent. Unused heat generated in industrial processes has a negative impact on the environment.

By using a Waste recovery steam generator, part of the heat is returned to the system and primary energy sources are saved. This sustainable use of energy is not only attractive from an environmental point of view. The use of process and exhaust air heat or hot exhaust gases generated in industrial processes also reduces operating costs. A plant often pays off within just a few months.

The flame-tube boilers from Achenbach are fired with gas or oil if no waste heat is available.

Put simply, water vapour is produced under increased pressure in a steam boiler. This produces temperatures well above the atmospheric boiling point of 100 degrees Celsius. While a conventional pressure cooker usually has an overpressure of around 0.8 bar, which increases the boiling temperature to around 116 degrees Celsius, Achenbach's flame-tube boilers reach an overpressure of up to 30 bar with boiling temperatures of up to 235 degrees Celsius and evaporation of up to 30,000 liters per hour.

The 4-pass Hybrid Steam Boiler is the solution if waste heat from an industrial process is to be used in an energy-efficient manner, but the hot waste heat stream is not continuously available in sufficient quantity. If the waste heat fails, the fossil-fired part of the steam boiler automatically takes over the steam supply.

The four-pass hybrid boiler from Achenbach thus combines the advantages of a waste heat steam generator with those of a steam boiler fired by gas or oil. Thanks to its hybrid function, the boiler is constantly at operating temperature. If a cold start is required, the boiler is started with fuel and the exhaust gas flow is switched on at operating temperature.