Mathematical Modelling of a Reduced Thermal Energy Consuming Spray Dryer for Evaporating Caustic Soda Solution

摘要

Experimental demonstration, mathematical modelling and simulation of a technique for reducing thermal energy consumption in the diaphragm cell process using a techno-economically viable process to produce 73% wt. NaOH from electrolytic diaphragm cell catholytes of about 10% wt. NaOH was carried out in this work. The technique completely eradicated the use of thermal energy in concentrating catholyte effluents from about 10% wt. NaOH solution to 50% wt. NaOH solution. This resulted in a specific energy savings of about 2.68×10~6 J/kg NaOH. The use of a spray dryer for increasing the concentration of 50% wt. NaOH solution to 73% wt. NaOH solution further improved the energy savings compared to that of multiple effect evaporators by 1.41×10~6 J/kg of solution, which corresponds to about 61.05% specific energy savings. The deviation of all simulated results from experimental data was between -0.062 and +0.084, portraying a good predictive tool for probing into the spray dryer operations. This work is expected to reduce considerably the total energy consumption of the diaphragm cell process through process integration or new processing methodology, with improved equipment designs.