Quality, long service life and functionality – these are the requirements that you have of an air heater. With its modern design and production concept, STELA has dedicated itself to delivering these features. Essentially, there is a technical distinction between two types of air heater:
Direct air heater
Direct STELA air heaters are fired by oil or gas fuels. They are used to create hot air for STELA drying systems and for use in other industrial processes, such as the brick-making industry.
Hot air generation with direct air heaters
The direct air heater consists of an outer casing, an intermediate casing to prevent radiation losses and a perforated firing chamber made of heat-resistant steel, which is located in the centre of the casing. The hot combustion gases are mixed with the fresh air heated on the wall of the firing chamber, and hot air with an even temperature is generated. The combustion energy is thus fed directly into the dryer. The technical firing efficiency is 100%.
Indirect air heaters
Indirect STELA air heaters are used in processes in which the mixture of flue gas with the air to be heated is undesirable. STELA air heaters are TÜV-tested and at discharge air temperatures up to 120°C have an efficiency over 90%. All indirect air heaters can be switched to direct mode.
Indirect mode Direct mode
Hot air generation with indirect air heaters
An indirect air heater consists of an outer casing, an intermediate casing to prevent radiation losses, gas flues and an enclosed firing chamber made of extremely heat-resistant steel, positioned in the centre of the casing. In an indirect air heater, the heat energy is transmitted to the fresh air exclusively through the heat exchanger surfaces of the enclosed firing chamber and the gas flues. The cooled combustion gases are discharged via a chimney into the open air. The hot air is thus entirely free of flue gases.