Energy Saving Options For Glass Furnaces & Recovery Of Heat From Their Flue Gases And Experiences With Batch & Cullet Pre-Heaters Applied In The Glass Industry

Several measures, such as changes in batch composition (less batch humidity), or optimisation of operating conditions, and limiting the combustion air excess, can lead to typically 2-8% of energy savings of industrial glass furnaces. Larger energy savings are only possible by new furnace designs, more insulation, increased cullet ratios or extra recovery of the heat contents of the flue gases. The flue gas heat contents, downstream regenerators or recuperators of air-fired furnaces or downstream flue gas heat contents, downstream regenerators or recuperators of air-fired furnaces or downstream the exhaust of oxygen-fired glass melting furnaces, can be exploited to preheat batch and cullet up to 275-350 deg C for regenerative furnaces and up to more than 500 deg C for recuperative and oxygen-fired furnaces. Above 550-600 deg C, the batches may start to show sticking behaviour. Energy savings of 12-20% have been reported for regenerative air-fired glass furnaces after connecting a batch and pellet-preheat system. The highest savings in the consumption of specific energy can be achieved by combining the application of batch and cullet preheating with an increased pull rate. Increased pull rates of more than 10% have been achieved and this potential of increasing production in the same furnace will improve economies of batch/cullet pre-heaters. The payback of the capital costs of batch and cullet pre heating systems by energy cost savings may take more than 3-4 years, depending on the energy prices & modifications required to the batch and flue gas channel systems.