The electric forehearth heating, also called forehearth boosting, is used to improve the glass quality / homogeneity. With specially designed molybdenum forehearth electrodes, the power will be inserted into the glass. For easier installation, the molybdenum electrodes are available with or without coating.
1 Molybdenum electrode
2 Adapter piece
3 Connection rod heat-resistant steel
4 Mechanical fixation
5 Electrical connection
6 Electrical insulation
7 Power cable
The forehearth electrodes are installed in the equalising section of the forehearth. A standard boosting installation consists of four electrodes per side / eight per forehearth, upon customers' request, other quantities are also possible. The electrodes have a diameter of 45 mm and the installation holes are cooled via air (cooling water is not necessary).
The boosting system consists of three main components:
To avoid any magnetic field disturbances / power losses, the transformers are located as close as possible to the forehearth. Each transformer has two secondary coils (2x20kVA) and is built inside a closed housing.
The transformers are connected to a thyristor power controller which can steplessly control the power. The cabinet is considered to control the boosting via a SCADA / PLC system or to control it by manual mode. For each electrode pair, the current and voltage will be measured and indicated individually.
EQS boosting system recommendations from HORN®:
HORN® standard EQS boosting system installation basics: