Exergy-based indicators to evaluate the possibilities to reduce fuel consumption in lime production

A new way to evaluate the energetic performance of lime shaft kilns is proposed. Two new exergy-based indicators are introduced for the evaluation, one to assess the exergy efficiency of limekilns and the other indicator to assess the effectiveness of the exergy consumption of the dissociation reaction. The combination of both indicators provides a clear picture of the energetic performance of the process, highlighting the main potentialities for fuel saving (fuel consumption represents about 50% of total production costs).The validity of the proposed assessment is examined using some operating data measured in a commercial lime factory. Results show that introduction of exergy-based indicators in the assessment improves the evaluation of the energy consumption of the calcination process. In this way the impact of the process losses in the fuel consumption is better addressed.

► This paper proposed a novel approach for the evaluation of the energetic performance of lime shaft kilns.
► The exergy efficiency indicator permits to highlight the principal opportunities of fuel saving by addressing the main areas of heat dissipation.
► The exergy efficiency indicator also allows the assessment of processes where the product is not valuated for its exergy content.
► The indicator for the exergy effectiveness of the dissociation reaction allows to assess the productivity of the limekiln.
► The results obtained shown that the operation of the cooling zone strongly influences the energetic performance of lime shaft kilns.