Analysis on Energy Consumption for Alumina Production Basing on Exergy Intensity-Energy Intensity-Product Ratio Analysis Model

Energy consumption has taken more and more attention in process industries to enhance their competitiveness in the world. An effective analysis method will be very helpful to provide the direction of energy saving for a plant. Exergy analysis method was introduced into energy intensity-product ratio analysis model (e-p analysis model), and exergy intensity-energy intensity-product ratio analysis model (d-e-p analysis model) was developed in this paper. Energy consumption of an alumina plant which adopts the combined Bayer and sinter method was calculated as a case study based on the d-e-p analysis model. The result shows that slurry sintering (SS), tube digestion (TD), aluminium trihydrate calcining (TC) and evaporation (EP) have the highest comprehensive exergy intensity in the nine unit processes, and the level of its energy utilization is influenced by the energy efficiency and product ratio in the plant. Energy saving brought out by technical innovation in unit process is perhaps covered because of the increasing of product ratio. Exergy loss and the distribution of exergy loss in the alumina plant were studied and the direction of energy saving can be found from the results.