Glass melting furnace

This temperature is determined by the composition of the batch and by the required amount of molten glass - the daily production - as well as the design-related energy losses.

Glass furnaces are operated with a flue gas heat recovery system to increase the energy efficiency.

The reduction in CO2 emissions required, due to the climate change mitigation, has led to various concepts to reduce or replace the use of fossil fuels, as well as to avoid the CO2 released during the melting of the batch through an increased recycling content.

Since the refractory material typically cannot tolerate large temperature changes and this leads to increased corrosion (consumption) of the same, such rapid cooling cannot occur anyway.

The heat source in 2021 is typically natural gas, heavy and light oil, and electric current fed directly into the glass bath by means of electrodes.

Using pure oxygen instead of air to burn fossil fuels (preferably gas) saves energy and, in the best case, reduces operating costs.

Typically, the size of a furnace is classified by its production capacity in metric tonnes per day (MTPD).

2% energy savings for every 10% cullet), the heating of the combustion air to a temperature level as high as possible by means of using a regenerative or a recuperator system is a fundamental part of the process.

In the most commonly used regenerator, the hot exhaust gases (1300 °C - 1400 °C) are fed discontinuously in chambers through a latticework of refractory, rectangular or special shaped bricks.

65% A recuperator operates continuously and consist of a metallic heat exchanger between the exhaust gas and fresh air.

In the case of structural restrictions for the installation of a regenerator, a combinations of regenerator and recuperator have also been developed and implemented in order to achieve the most energy-saving or efficient operation of the system possible[6] As a further measure, in order to utilize the heat content of the exhaust gas (temperature > 700 °C), a downstream heat/power coupling is technically possible or has already been tested on a large scale.

Innovative revisions of this concept must be tested in practice in the productive environment in the long term at great expense.

However, this requires a certain willingness to take risks on the part of the companies, which, due to the fierce competition in this industry, is generally not taken.

Triggered by the climate debate, several developments and research projects have now been launched to significantly reduce the climate-damaging CO2 in production.

[7] Various European glass manufacturers are working on this project together with technology suppliers with the aim of realizing a corresponding plant on an industrial scale.

This glass melting so called Hybrid-Furnace will be operated with 80% electricity generated from renewable energy sources and is expected to enable a reduction of CO2 by 50%.

[8][9] The industry, a community of interest of 19 European container glass companies, tried to be supported financially by the EU Innovation Fund.

[12] Furthermore, there are research projects to heat glass melting furnaces alternatively with so-called green hydrogen.

However, this can lead to increased vibrations, mainly caused by the existing installations in the pipeline, which promote the formation of cracks and thus trigger major damage events in the long term.

However, the required gas quantities were not fully available for a longer period of time, so that the large-scale test was limited to 4 days.