Evaluation of the Drying Process at Alufluor AB

Abstract: Due to the act on Energy Audits in Large Enterprises (EKL) that came into effect on the 1st of June in 2014, all larger companies are obligated to perform an energy audit every four years. Parallel to the audit performed at Alufluor AB this more detailed audit of the drying part of their process was carried out. This as the drying part is energy intensive and is responsible for the majority of the energy consumed in the process. The thermal decomposition of the intermediate product, aluminum fluoride trihydrate (AlF3ᐧ3H2O), was investigated through thermal studies. The dehydration process described in literature was confirmed by the experiments and the enthalpy of dehydration was measured to 2660 kJ/kg water. A theoretical minimum value of 0,58 MWh/ton product for the overall drying process was estimated. The results of the thermal studies can be used when designing a new drying process or when replacing current unit operations. An energy mapping of the thermal and electrical energy consumers was performed and the efficiency of the thermal unit operations were estimated. It was concluded that replacing the current centrifuge with a new unit would decrease the natural gas consumption in the following step by 23,6 % per year. This would give the investment a payback time of 4,2 years.