Analysis of potassium nitrate purification with recovery of solvent through single effect mechanical vapor compression

Analysis of purification of potassium nitrate with incorporation of single effect mechanical vapor compressor for solvent recovery was done. Analysis focused on the effect of concentration and temperature of mother liquor on the energy efficiency of the process and the amount of recovered solvent. Performance coefficient of mechanical vapor compressor ranged between 1.5 and 7.5 depending primarily on the temperature of mother liquor. It was found that with increase in temperature of mother liquor through pre-heating, the power of the compressor, compression ratio and amount of heat supplied to the evaporator decrease. For a 40% concentrated feed solution and mother liquor temperature above 80 °C, performance coefficient is higher than 4. It is therefore concluded that preheating mother liquor and reduction of the effect of concentration of both mother liquor and concentrated waste stream through other methods reduces the power consumption of purification process.