Raising efficiency by an optimized filters purification system using waste heat in metal industry
Joh. Pengg AG, headquarters at Thörl in Styria, is specialized in production of oil-tempered spring wires for automobile, electrical, and mechanical engineering industry. Production of such wires is an energy intensive process with several heating, cooling, and shaping production steps. In this process separation and disposal of production residues are of economical and ecological importance.
To separate solid residues from waste water of a neutralization plant a cell filter press is used. The filter residues are removed once a day:
- Dehydration of the filter residues with compressed air (7 bar) down to a water content of some 80 %, and
- manual removal of the residues from the filter mat.
The aim of the project was the minimization of compressed air consumption and the reduction of disposal costs by drying the filter residues using waste heat.
The cell filter press has been equipped with measurement devices to monitor the compressed air and the dehydration process in different filter cells. Furthermore pressure, speed and delivery rate of the filter pump during filtering cycles have been measured continuously. Investigations of drying filter residues in a drying cell (hot air, 150 °C) have been carried out.
Results show, that drying of filter residues in a drying cell is possible and will lead to a saving of some 10.000,-- € a year.
Diagrams to determine optimum duration of treatment of filter cells with compressed air have been provided.
Joh. Pengg AG
Tel.: +43 (3861) 5090-0
Fax: +43 (3861) 2318
Institut für Energieforschung
Elisabethstraße 5, A-8010 Graz
Tel.: +43 (316) 876-1328
Fax: +43 (316) 876-1320