Optimal use of the energy in glass melting through waste gas heat recovery.
Due to process constraints, 25% of the energy used to melt glass escapes with waste gases. The goal of research conducted by Nikolaus Sorg GmbH & Co. KG (SORG) was to recover the maximum amount of energy possible and to return it directly to the process.
Batch preheating with waste gasses is the preferred method for recovering energy. Many patents and solutions to this problem can be found. In implementation, however, many attempts have failed. The reason is due to poor flow characteristics of the raw materials in a heat exchanger. In addition, the mixture of raw materials together with the moisture found in cullet leads to the formation of a material similar to cement. This causes clumping and blocks the material flow. Due to this problem, past attempts at batch preheating have not been financially viable.
The invention of new technology expands the available applications in the glass industry to sectors where preheating was never possible for the above mentioned reasons. The new technology developed by SORG allows for the first time an interruption free operation. This concept employs multiple heat exchangers in a modular concept that is dust-free. The waste gas is directed in a counter-flow to the glass batch materials. This new method of directing the waste gasses together with mechanically vibrating the heat exchangers eliminates previous limits on the application.
This allows a continuous operation without problems on new applications where high moisture content is present or where little cullet is available. The test unit developed on-site has been scaled up and has proven itself under full-scale industrial conditions. Through the improved design, the continuous flow of material is ensured, and the “cement phase” that leads to blockage is avoided.
This development makes it possible to use batch preheating for all sectors of the glass industry. Up until now this was only possible in very limited applications due to constraints.
Glass operations gain the following advantages through the installation of a batch preheater: reduced energy consumption, increased production on an existing furnace, and reduced use of electricity. Additionally, an upgrade to this technology in existing factories could compensate for the increased energy consumption of aging furnaces.