Summary

Twelve galvanizing companies have conducted a survey how to optimize their energy consumption. The objective has been the recovery of heat from the flue gases coming from the galvanizing furnaces. The investigation results in two practical possibilities for reusing the heat of the flue gases: the heating of bathes for pre-treatment and the heating of air for the dryers.
The installation of a hot water circuit for transporting the heat from the flue gases to the bathes for pretreatment, provides an advantage in case the surface of the galvanizing bath is larger than 10 m². The investment is estimated on €  47,000. The saving lies between 58,000 and 100,000 Nm³ natural gas pro year pro galvanizing bath. This depends on the surface of the bath: 10 tot 15 m². If we calculate with a gas price of €  0.13 pro Nm³, the financial saving amounts to € 7,500 up to €  13,000 pro year pro galvanizing bath. The pay-back time varies between 3.6 and 6.3 years.
Actually, the pay-back time will be shorter because the additional saving by heating the air for the dryers has not yet taken into account. During this survey the advantage of energy conservation for the dryers could not be confirmed sufficiently, because the demand for heat by the dryers fluctuates strongly.