Summary
In the course of an R&D project at Glashütte Gerresheim, in Düsseldorf, a regenerative, cross-heated melting bath was replaced by an oxygen-fired bath.
The five main elements of this innovative type of melting bath are
- the melting bath,
- the air separation plant,
- the heating system,
- the exhaust gas system and
- the melt pre-warming system.
The melting bath is designed for a specific melt throughput of
2.7 Mg/m² x d. 400 Mg of container glass can be melted daily for the production of glass jars or soft drink and mineral water bottles. The heating uses a mixture of oil-gas and oxygen, which at this time was an innovation.
Results:
- The oxygen-fired glass melting bath went into operation without much difficulty. In normal operation the smelting is stable. Fluctuations in the bath load of more than 20 Mg/day, can be coped with without negative influencing glass quality.
- Using this melt technology offers the following improvements of the container glass forming process in comparison to conventional baths:
- NOx -emissions can be reduced to 500 mg/Nm³ or 0.7 kg/Mg melted glass, the NOx-reduction is thus about 70%.
- The energy demand is reduced to approx. 750 kcal/kg glass, which represents an energy saving of approx. 25%. Waste heat should be used to pre-heat the melting charge, because this is more effective than power or steam generation.
- The construction of the melting oven is simplified, because this type of oven requires no regenerative chambers. This means that less space is required for the melting process, and when it comes to servicing there will be no additional costs for the disposal of contaminated regenerative chambers.
- With constant heating of the bath from both sides in a continuous process, the melting is easier to control. The continuous heating produces evenly-formed glass drops, so that overall the production yield is greater than with conventional processes.
- When selecting refractory materials it is important to ensure high levels of acid resistance.
- Because of the success of this production-integrated approach to environmental protection, the Gerresheimer Group followed this project up by immediately planning a further oxygen-fired special glass bath in Pisa.
