Fans installed throughout the process are usually of a centrifugal type. At the start of the process, a large centrifugal fan is used to cool the oven walls. A high pressure fan is installed to introduce fresh air inside the oven to allow for correct combustion. The following fan is a high temperature type (400 to 500°C), exhausting hot gasses from the oven. Inside the oven itself, some recirculating fans are often used to maintain a homogenous temperature.
Following the oven, depending on glass type, either: Glass is slowly cooled directly after the oven through medium pressure / high volume centrifugals (windows, flat glass), or through high pressure types in the case of the car glass industries for example. Glass flows from the ovens to be distributed in different moulds, such as in bottle production.
In this case, boilers are installed along the process to maintain liquid glass at the right temperature. Fans provide fresh air to the boilers and are called “conveyors”. The final fans installed in this system are high pressure blowers for mould cooling. A “flat aerodynamic curve” is needed to keep the same pressure on the different moulds, whatever the number of moulds installed or which are functioning at the same time.
Fans are of a quite heavy duty type, and have to be robust, efficient and reliable. A complete range of motor powers is also necessary up to a few hundred kWs. Direct, belt and coupling drive arrangement are needed because of temperature, mechanical life time and cycle conditions.